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dtc troubleshooting index

1. HUMIDITY IN CAR TEMPERATURE SENSOR 4P CONNECTOR Wire side of female terminals Fig 44 Identifvine Continuity Between No 5 And Humidity In Car Temperature Sensor 4P Connector No 4 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 9 NO Repair open in the wire between the climate control unit and the in car temperature sensor 9 Check for continuity between climate control unit connector A 40P No 8 terminal and the humidity in car temperature sensor 4P connector No 3 terminal CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Dga ajz EG fd RED n Tl n 1121314 HUMIDITY IN CAR TEMPERATURE SENSOR 4P CONNECTOR Wire side of female terminals 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 45 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And No 3 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P and at the humidity in car temperature sensor 4P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire between the climate control unit and the in car temperature sensor DTC B1226 OR DTC
2. BUD REAR AIR MIX CONTROL MOTOR 7P CONNECTOR Wire side of female terminals CLIMATE CONTROL UNIT CONNECTOR B 14 Wire side of female terminals Fig 95 Identifying Continuity Between Climate Control Unit A 40P B 14P And Rear Air Mix Control Motor 7P Connector Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P B 14P and at the rear air mix control motor 7P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire s between the climate control unit and the rear air mix control motor DTC B1245 OR DTC INDICATOR G A SHORT IN THE REAR AIR MIX CONTROL MOTOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B1245 or G indicated YES Go to step 5 NO Intermittent failure 2008 Acura MDX 2007 09 HVAC Climate Control MDX 5 Check for DTCs Are these DTCs also present B1234 or and AUTO and or B1237 or N and AUTO and or B2968 or A and WINDSHIELD DEFROST and or
3. INC Is there battery voltage 12 13 14 15 16 17 18 19 20 21 22 2008 2007 09 HVAC Climate Control YES Go to step 12 NO Go to step 36 Turn the ignition switch to LOCK 0 Reinstall the A C condenser fan relay Jump the SCS line with the HDS NOTE This step must be done to protect the powertrain control module PCM from damage Disconnect PCM connector A 49P Connect PCM connector A 49P No 4 terminal to body ground with a jumper wire PCM CONNECTOR A 49 Terminal side of female terminals Fig 144 Identifying PCM Connector A 49P No 4 Terminal To Body Ground Courtesy of AMERICAN HONDA MOTOR INC Turn the ignition switch to ON II Do the A C condenser and radiator fans run on low YES Check for loose wires or poor connections at PCM connector A 49P terminal No 4 If the connections are good substitute a known good PCM and recheck If the symptom indication goes away replace the original PCM see PCM REPLACEMENT NO Repair open in the wire between the A C condenser fan relay and the PCM Disconnect the jumper wire Reinstall the A C condenser fan relay Disconnect the A C condenser fan 2P connector Turn the ignition switch to ON then set the A C button and fan control button ON Measure the voltage between the A C condenser fan 2P connector No 2 terminal and body ground 2008 Acura MDX 2007
4. INC 7 Remove the hood latch see HOOD LATCH REPLACEMENT 8 Remove the A C condenser A by lifting it up Be careful not to damage the radiator and A C condenser fins when removing the A C condenser Fig 222 Identifying A C Condenser Courtesy of AMERICAN HONDA MOTOR CO INC 9 Install the A C condenser in the reverse order of removal and note these items e If you re installing a new A C condenser add refrigerant oil DENSO ND OIL 8 see A C REFRIGERANT OIL REPLACEMENT e Replace the O rings with new ones at each fitting and apply a thin coat of refrigerant oil before installing them Be sure to use the correct O rings for HFC 134a R 134a to avoid leakage e Immediately after using the oil reinstall the cap on the container and seal it to avoid moisture absorption e Do not spill the refrigerant oil on the vehicle it may damage the paint if the refrigerant oil contacts 2008 Acura MDX 2007 09 HVAC Climate Control MDX the paint wash it off immediately e Be careful not to damage the radiator or the A C condenser fins when installing the A C condenser e Charge the system see SYSTEM CHARGING e Adjust the hood latch see HOOD ADJUSTMENT RECEIVER DRYER DESICCANT REPLACEMENT NOTE Install the receiver dryer as quickly as possible to prevent the system from absorbing moisture from the air 1 Remove the A C condenser see A C CONDENSER REPLACEMENT 2 Remove the cap A from the bo
5. 2008 Acura MDX 2007 09 HVAC Climate Control MDX 23 Test the rear power transistor see REAR POWER TRANSISTOR TEST Is the rear power transistor OK YES Check for loose wires or poor connections at climate control unit connector B 14P and at the rear power transistor 4P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the rear power transistor see REAR POWER TRANSISTOR TEST 24 Disconnect the jumper wire 25 Disconnect the rear blower motor 2P connector 26 Measure the voltage between the rear blower motor 2P connector No 1 terminal and body ground REAR BLOWER MOTOR 2P CONNECTOR V GRY Wire side of female terminals Fig 40 Measuring Voltage Between Rear Blower Motor 2P Connector No 1 Terminal And Bod Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Replace the rear blower motor see REAR CLIMATE CONTROL PANEL REMOVAL INSTALLATION NO Go to step 27 27 Turn the ignition switch to LOCK 0 28 Remove the rear blower motor relay from the dashboard wire harness and test it see POWER RELAY TEST Is the relay OK YES Go to step 29 NO Replace the rear blower motor relay 29 Measure the voltage between the rear blower motor relay 4P socket No 1 terminal and body ground 2008 Acura MDX 2007
6. 4 Remove the wire harness clips A the self tapping screws and the passenger s heater duct B Fig 185 Identifying Wire Harness Clips And Passenger sHeater Duct With Screws Courtesy of AMERICAN HONDA MOTOR INC 5 Disconnect the connector from the front blower motor Remove the wire harness clips B 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 186 Identifying Front Blower Motor Connector And Wire Harness Clips Courtesy of AMERICAN HONDA MOTOR INC 6 Disconnect the connectors A from the recirculation control motor and adaptive front lighting control unit then remove the harness clip B Remove the self tapping screws the mounting nuts and the blower unit C 9 8 N m 1 0 kgf m 7 2 Ibf ft Fig 187 Identifying Recirculation Control Motor Connector Harness Clip And Blower Unit With Screws With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 7 Install the unit in the reverse order of removal Make sure that there is no air leakage BLOWER UNIT COMPONENT REPLACEMENT 2008 Acura MDX 2007 09 HVAC Climate Control MDX Note these items when overhauling the blower unit e The recirculation control motor A front blower motor B and the dust and pollen filter C can be replaced without removing the blower unit e Before reassembly make sure that the recirculation control linkage and door move smoothly without binding e After reassembl
7. CLIMATE CONTROL UNIT CONNECTOR A 40 a TeTe Te iT Tw Te Tv Tw w L7 Le m o m mo e m eT wi Wire side of female terminals Fig 122 Measuring Voltage Between Body Ground And Climate Control Unit Connector A 40P 2008 Acura MDX 2007 09 HVAC Climate Control MDX No 26 Terminal Courtesy of AMERICAN HONDA MOTOR INC 15 there any voltage YES Repair short to power in the wire between the climate control unit and the A C pressure sensor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Go to step 12 12 Turn the ignition switch to LOCK 0 13 Reconnect climate control unit connector A 40P 14 Turn the ignition switch to ON II 15 Measure the voltage between climate control unit connector A 40P No 6 and No 8 terminals and between climate control unit connector A 40P No 8 and No 26 terminals CLIMATE CONTROL UNIT CONNECTOR A 40P 1515 DERE Dag LT GRN Cal EEA Wire side of female terminals Fig 123 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 And No 8 And No 26 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there about 5 V YES Replace the A C pressure sensor NO Check for loose wires or poor connections at climate control unit connector A 40P and at the A C pre
8. Wire side of female terminals Fig 22 Identifying Rear Climate Control Panel 10P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC REAR CLIMATE CONTROL UNIT INPUTS AND OUTPUTS LT BLU ILLUMI INPUT 9 CLIMATE CONTROL UNIT A C BUS TX INPUT OUTPUT ORN CONTROL UNIT A C BUS RX INPUT OUTPUT CIRCUIT DIAGRAM 2008 Acura MDX 2007 09 HVAC Climate Control MDX AAN UNDER HOOD LOK BATTU No 2 PRELONGO 20 AL e Ne 1 TON Mo 7 7 5 A FUSE MODULE RELAY BLOCK the UNDER HOOD FUSE RELAY BOK Fig 23 Climate Control Circuit Diagram 1 Of 4 Courtesy of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX we Pun CUMATE CONTROL E iT can RU Gm GEN ex MOi MODES 0 M VENT MODES wo FRONT OUTSBEAR an EVAPORATOR TEMPERATURE Ls FRONT MODE CONTROL MOTOR RECRICULATION CONTROL MOTOR 5 lt 0 5 lt 0 7 Fig 24 Climate Control Circuit Diagram 2 Of 4 Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX M CUMATE CONTR E UNIT AM al n rn In IE W 2 p ae m Au An 52 EL A
9. f HANAN 1921 Delle elsene AA PNK l Wire side of female terminals Fig 50 Identifying Continuity Between Climate Control Unit Connector A 40P No 28 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the outside air temperature sensor NO Go to step 9 9 Check for continuity between climate control unit connector A 40P No 8 and No 28 terminals 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 Wire side of female terminals Fig 51 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And No 28 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short in the wires between the climate control unit and the outside air temperature sensor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1229 OR DTC INDICATOR E AND AUTO AN OPEN IN THE SUNLIGHT SENSOR CIRCUIT l Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNO
10. 3 Ifthe front mode control motor did not run in step 2 remove it then check the front mode control linkage and doors for smooth movement e If the linkage and doors move smoothly replace the front mode control motor see FRONT MODE CONTROL MOTOR REPLACEMENT e If the linkage or doors stick or bind repair them as needed e If the front mode control motor runs smoothly go to step 4 4 Usea digital multimeter with an output of 1 mA or less at the 20 kohms range With the front mode control motor running as in step 2 check for continuity between the No 3 4 5 and 6 terminals and the No 7 terminal individually There should be continuity for a moment at each terminal as the motor moves past the switch s terminal 5 If there is no continuity for a moment at each terminal replace the front mode control motor see FRONT MODE CONTROL MOTOR REPLACEMENT FRONT MODE CONTROL MOTOR REPLACEMENT 1 Remove the glove box see GLOVE BOX REMOVAL INSTALLATION 2 Disconnect the 7P connector A from the front mode control motor B Remove the self tapping screws and the front mode control motor from the heater unit 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 177 Identifying Front Mode Control Motor And 7P Connector With Screws Courtesy of AMERICAN HONDA MOTOR CO INC 3 Install the motor in the reverse order of removal Make sure the pin on the motor is properly engaged with the linkage After installation
11. Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check the DTCs Is DTC B2983 or K indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the recirculation control motor circuit Turn the ignition switch to LOCK 0 Test the recirculation control motor see RECIRCULATION CONTROL MOTOR TEST Is the recirculation control motor OK YES Go to step 7 NO Replace the recirculation control motor see RECIRCULATION CONTROL MOTOR REPLACEMENT or repair the recirculation control linkage or door Disconnect the recirculation control motor 7P connector 2008 Acura MDX 2007 09 HVAC Climate Control MDX 8 9 10 Disconnect climate control unit connector 40 Check for continuity between the following terminals of climate control unit connector A 40P and the recirculation control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals 1 7 T YEL ORN Jr HE RECIRCULATION CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 130 Identifying Continuity Between Climate Control Unit A
12. Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the rear power transistor NO Go to step 19 Check for continuity between the following terminals of climate control unit connector B 14P and the rear power transistor 4P connector 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of fernale terminals 13 RED BLU REAR POWER TRANSISTOR CONNECTOR Wire side of female terminals Fig 38 Identifying Continuity Between Climate Control Unit B 14P And Rear Power Transistor 4P Connector Terminal Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 20 NO Repair open in the wire s between the climate control unit and the rear power transistor 20 Turn the ignition switch to ON II 2 Measure the voltage between body ground and climate control unit connector B 14P No 13 and No 14 terminals individually CLIMATE CONTROL UNIT CONNECTOR B 14P ela gt AAT 2 RED BLU YW Wire side of fernale terminals Fig 39 Measuring Voltage Between Body Ground And Climate Control Unit Connector B 14P No 13 And No 14 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC 15 there any voltage YES Repair short to power in the wire s NO Go to step 22 22 Reconnect climate control unit connector 14
13. 2008 Acura MDX 2007 09 HVAC Climate Control MDX 2007 09 HVAC Climate Control MDX COMPONENT LOCATION INDEX SERVICE VALVE HIGH PRESSURE SIDE tower VALVE ILOW PRESSURE SIDE FRONT EVAPORATOR CORE Located in the heater unit NO FRONT EXPANSION VALVE x M 2 EA Located in the front evaporator RECEIVER DRYER DESICCANT A C CONDENSER A C COMPRESSOR Fig 1 Identifying Climate Control Component Location 1 Of 3 Courtesy of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX FAN CONTROL RELAY A C COMPRESSOR CLUTCH RELAY A C CONDENSER FAN RELAY RADIATOR FAN RELAY FRONT BLOWER MOTOR RELAY A C DIODE A UNDER HOOD FUSE RELAY BOX A C DIODE B A C PRESSURE SENSOR X Rey d OUTSIDE AIR TEMPERATURE SENSOR RADIATOR FAN A C CONDENSER FAN Fig 2 Identifying Climate Control Component Location 2 Of 3 Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX SUNLIGHT SENSOR HEATER VALVE FRONT EVAPORATOR CORE CABLE Located in the heater unit HEATER UNIT CORE Eas ee FRONT MODE CONTROL MOTOR BLOWER UNIT V N POLLEN FILTER GRO 2 7 NOH IM dx TIN ZL 4 N 2 ww BMC 14 L RECIRCULATION A CONTROL MOTOR DRIVER S AIR MIX aye y CONTROL M
14. Check for loose wires or poor connections at climate control unit connector A 40P and at the outside air temperature sensor 2P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire between the climate control unit and the outside air temperature sensor DTC B1228 OR DTC INDICATOR D AND AUTO A SHORT IN THE OUTSIDE AIR TEMPERATURE SENSOR CIRCUIT l 2 3 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1228 or D and AUTO indicated 2008 Acura MDX 2007 09 HVAC Climate Control MDX YES Go to step 5 NO Intermittent failure 5 Turn the ignition switch to LOCK 0 6 Remove the outside air temperature sensor see OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT and test it see OUTSIDE AIR TEMPERATURE SENSOR TEST Is the outside air temperature sensor OK YES Go to step 7 NO Replace the outside air temperature sensor 7 Disconnect climate control unit connector A 40P 8 Check for continuity between climate control unit connector A 40P No 28 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P
15. Go to step 12 12 Turn the ignition switch to ON and measure the voltage between climate control unit connector A 40P No 27 terminal and body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 Te TZ Te 991 Te Ts To To To 7T Bis YEL Wire side of female terminals Fig 113 Measuring Voltage Between Climate Control Unit Connector A 40P No 27 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC 15 there any voltage YES Repair short to power in the wire between the climate control unit and the humidity sensor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit 13 Turn the ignition switch to LOCK 0 and disconnect climate control unit connector A 40P 14 Disconnect these items e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor 15 Check for continuity between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals Fig 114 Identifying Continuity Between Climate Control Unit Connector A 40P
16. Grr YE Bu qv ary oom DRIVER S AR MOTOR Fig 25 Climate Control Circuit Diagram 3 Of 4 Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX No 22 7 5 Al FUSE tn the y fight rali Fig 26 Climate Control Circuit Diagram 4 Of 4 Courtesy of AMERICAN HONDA MOTOR CO INC DTC TROUBLESHOOTING DTC B1202 CLIMATE CONTROL UNIT INTERNAL ERROR NOTE Check the battery condition see BATTERY TEST and the charging system see CHARGING SYSTEM INDICATOR CIRCUIT TROUBLESHOOTING 1 Clear the DTC with the HDS 2008 Acura MDX 2007 09 HVAC Climate Control MDX 2 Turn the ignition switch to LOCK 0 and then ON II Wait for 6 seconds or more Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS Check for DTCs Is DTC B1202 indicated YES The climate control unit is faulty replace the climate control unit NO Intermittent failure the climate control unit is OK at this time DTC B1205 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH GAUGE CONTROL MODULE VSP NE MESSAGE DTC B1206 OR DTC INDICATOR AUTO CLIMATE CONTROL UNIT LOST COMMUNICATION WITH GAUGE CONTROL MODULE ECT MESSAGE DTC B1207 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH GAUGE CONTROL MODULE ILLUMI MESSAGE NOTE If you are troubleshooting multiple DTCs be sure to follow the ins
17. Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1215 OR DTC INDICATOR J AN OPEN OR SHORT IN THE RECIRCULATION CONTROL MOTOR CIRCUIT 1 2 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 2008 Acura MDX 2007 09 HVAC Climate Control MDX 4 Check for DTCs Is DTC B1215 or J indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the recirculation control motor circuit 5 Turn the ignition switch to LOCK 0 6 Test the recirculation control motor see RECIRCULATION CONTROL MOTOR TEST Is the recirculation control motor OK YES Go to step 7 NO Replace the recirculation control motor see RECIRCULATION CONTROL MOTOR REPLACEMENT 7 Disconnect the recirculation control motor 7P connector 8 Disconnect climate control unit connector A 40P 9 Check for continuity between the following terminals of climate control unit connector A 40P and the recirculation control motor 7P connector 40P 7P No 8 No 7 No 35 No 5 No 36 No 4 No 38 No 3 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECT
18. 0 7 Remove the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT and test it see HUMIDITY IN CAR TEMPERATURE SENSOR TEST 15 the humidity sensor OK YES Go to step 8 NO Replace the humidity in car temperature sensor Disconnect the humidity in car temperature sensor 4P connector Disconnect climate control unit connector A 40P 10 Check for continuity between body ground and climate control unit connector A 40P No 27 terminal 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 111 Checking Continuity Between Body Ground And Climate Control Unit Connector A 40P No 27 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the humidity sensor NO Go to step 11 11 Check for continuity between climate control unit connector A 40P No 6 and No 27 terminals CLIMATE CONTROL UNIT CONNECTOR A 40P GRY ae T A bh RET e To o YEL E Wire side of female terminals Fig 112 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 And No 27 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair the short in the wires NO
19. 40P And Recirculation Control Motor 7P Connector Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the recirculation control motor Check for continuity between body ground and climate control unit connector A 40P No 18 and No 19 terminals individually CLIMATE CONTROL UNIT CONNECTOR A 40P HO Wire side of female terminals Fig 131 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 40P No 18 And No 19 Terminals 2008 Acura MDX 2007 09 HVAC Climate Control MDX Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the recirculation control motor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B2991 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH AUDIO UNIT ON EA Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS Check for DTCs Is DTC B2991 indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the rear climate control panel and climate control unit circuit Turn the ign
20. 50 mL 1 2 3 fl oz Front Evaporator iO mL 1 1 3 fLoz RearEvaporator BO mL 1 10 mL 1 3 fl oz Leakage repair 25 mL 5 7 fl oz A C compressor For A C compressor replacement subtract the volume of oil drained from the removed A C 2008 Acura MDX 2007 09 HVAC Climate Control MDX compressor from 125 mL 4 2 9 fl oz and drain the calculated volumne of oil from the new A C compressor 135 mL 4 2 9 fl oz Volume of removed A C compressor Volume to drain from new A C commpressor NOTE Even if no oil is drained from the removed A C compressor don t drain more than 50 mL 1 2 3 fl oz from the new A C compressor REMOVED NEW AIC COMPREBSOR A C COMPRESSOR 5 5578 nates H SAME LEVEL 12 mL 4 2 9 faz Fig 4 Identifying Refrigerant Oil Level Courtesy of AMERICAN HONDA MOTOR INC FRONT A C LINE REPLACEMENT 2008 Acura MDX 2007 09 HVAC Climate Control MDX FRONT SUCTION LINE 42 R EUAN ANL A C PRESSURE SENSOR A C CONDENSER AJC lt e D Discharge hose to the A C compressor 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft 2 Discharge hose to the A C condenser 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft 3 Front receiver line to the A C condenser 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft A C pressure sensor to the front receiver line 11 x 1 0 mm 10 8 N m 1 1 kgf m 8 0 Ibf ft Front receiver lin
21. DTC B1232 OR DTC INDICATOR H AND AUTO A SHORT IN THE FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT 1 2 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1232 or H and AUTO indicated VES _ Goto sten 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Intermittent failure 5 Turn the ignition switch to LOCK 0 6 Remove the front evaporator temperature sensor see FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT and test it see FRONT EVAPORATOR TEMPERATURE SENSOR TEST Is the front evaporator temperature sensor OK YES Go to step 7 NO Replace the front evaporator temperature sensor 7 Disconnect climate control unit connector A 40P 8 Check for continuity between climate control unit connector A 40P No 24 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 58 Identifying Continuity Between Climate Control Unit Connector A 40P No 24 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the front evaporator temperature sensor NO Go to step 9 9 Check fo
22. Go to step 22 22 Reconnect climate control unit connector A 40P 23 Testthe front power transistor see FRONT POWER TRANSISTOR TEST Is the front power transistor OK YES Check for loose wires or poor connections at climate control unit connector A 40P and at the front power transistor 4P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the front power transistor see FRONT POWER TRANSISTOR TEST 24 Disconnect the jumper wire 25 Disconnect the front blower motor 2P connector 26 Measure the voltage between the front blower motor 2P connector No 1 terminal and body ground FRONT BLOWER MOTOR 2P CONNECTOR WHT y il Wire side of female terminals Fig 91 Measuring Voltage Between Front Blower Motor 2P Connector No 1 Terminal And Bod Ground Courtesv of AMERICAN HONDA MOTOR CO INC 22 28 29 30 21 2008 Acura MDX 2007 09 HVAC Climate Control MDX Is there battery voltage YES Replace the front blower motor see BLOWER UNIT COMPONENT REPLACEMENT NO Go to step 27 Turn the ignition switch to LOCK 0 Remove the front blower motor relay from the relay block and test it see POWER RELAY TEST Is the relay OK YES Go to step 29 NO Replace the front blower motor relay Measure the voltage between the front blower motor relay
23. INC 2 From under the dash disconnect the heater valve cable housing from the cable clamp A and disconnect the heater valve cable B from the driver s air mix control linkage C Fig 205 Identifying Cable Clamp Heater Valve Cable And Driver s Air Mix Control Linkage 2008 Acura MDX 2007 09 HVAC Climate Control MDX Courtesy of AMERICAN HONDA MOTOR INC 3 Set the temperature control dial to Max Cool Lo with the ignition switch to ON II 4 Attach the heater valve cable B to the driver s air mix control linkage C as shown step 2 Snap the heater valve cable housing into the cable clamp A NOTE Make sure the ring end of the cable is pushed all the way to the base of the pin on driver s air mix control linkage 5 From under the hood turn the heater valve arm A to the fully closed position as shown and hold it Attach the heater valve cable B to the heater valve arm and gently pull on the heater valve cable housing to take up any slack then install the heater valve cable housing into the cable clamp C Fig 206 Identifying Heater Valve Arm Courtesy of AMERICAN HONDA MOTOR CO INC A C COMPRESSOR REPLACEMENT NOTE Do not install the A C compressor into a system unless you are completely sure that the system is free of contamination Installing the A C compressor into a contaminated system can result in premature A C compressor failure 1 If the A C compressor is marginally op
24. If the symptom indication goes away replace the original rear climate control panel DTC B2967 OR DTC INDICATOR A AND WINDSHIELD DEFROST AN OPEN IN THE HUMIDITY SENSOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B2967 or A and WINDSHIELD DEFROST indicated YES Go to step 5 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Intermittent failure check for loose wires or poor connections on the humidity sensor circuit Turn the ignition switch to LOCK 0 Remove the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT and test it see HUMIDITY IN CAR TEMPERA TURE SENSOR TEST 15 the humidity sensor OK YES Go to step 7 NO Replace the humidity in car temperature sensor 7 Disconnect the humidity in car temperature sensor 4P connector Disconnect climate control unit connector A 40P 9 Check for continuity between the following terminals of climate control unit connector A 40P and the humidity in car temperature sensor 4P connector CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals Val a HUMIDITY IN
25. If you re installing a new front evaporator core add refrigerant oil DENSO ND OIL 8 see A C SERVICE TIPS AND PRECAUTIONS Replace the O rings with new ones at each fitting and apply a thin coat of refrigerant oil before installing them Be sure to use the correct O rings for HFC 134a R 134a to avoid leakage Immediately after using the oil reinstall the cap on the container and seal it to avoid moisture absorption Do not spill the refrigerant oil on the vehicle it may damage the paint if the refrigerant oil contacts the paint wash it off immediately Make sure that there is no air leakage Charge the system see SYSTEM CHARGING HEATER UNIT CORE REPLACEMENT SRS components are located in this area Review the SRS component locations see COMPONENT LOCATION INDEX and the precautions and procedures see PRECAUTIONS AND PROCEDURES before doing repairs or service 1 Do the battery terminal disconnection procedure see BATTERY TERMINAL DISCONNECTION AND RECONNECTION 2 Disconnect the front receiver line and front suction line from the front evaporator core see FRONT EVAPORATOR CORE REPLACEMENT 2008 Acura MDX 2007 09 HVAC Climate Control MDX 3 From under the hood open the cable clamp A then disconnect the heater valve cable B from the 6 heater valve arm C Turn the heater valve arm to the fully opened position as shown Fig 194 Turning Heater Valve Arm Courtesy of AMERICAN HONDA
26. Repair open in the wire between the A C compressor clutch relay and the A C compressor clutch HUMIDITY IN CAR TEMPERATURE SENSOR TEST HUMIDITY SENSOR TEST Remove the humidity in car temperature sensor sce HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT 2 Connect the humidity in car temperature sensor 4P connector 3 Turn the ignition switch to ON II Measure the voltage between the terminals with the probe on the No 2 terminal and the probe on the No 3 terminal with the connector connected VOLTAGE IN EN AA MS m 0 20 40 60 80 100 HUMIDITY LEVEL rh Fig 160 Measuring Voltage Between Terminals With Probe On No 2 And Probe On No 3 Terminal 2008 Acura MDX 2007 09 HVAC Climate Control MDX Courtesy of AMERICAN HONDA MOTOR INC 4 Ifthe voltage is not as specified replace the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT IN CAR TEMPERATURE SENSOR TEST 1 Remove the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT 2 Connect the humidity in car temperature sensor 4P connector 3 Test the humidity in car temperature sensor while holding it in front of the dashboard center vent e Measure the resistance with the system set to Max Cool e Measure the resistance with the system set to Max Hot 4 Compare the resistance reading betwe
27. SYSTEM CHARGING CAUTION e Air conditioning refrigerant or lubricant vapor can irritate your eyes nose or throat 2008 Acura MDX 2007 09 HVAC Climate Control MDX Be careful when connecting service equipment e Do not breathe refrigerant or vapor NOTE e If accidental system discharge occurs ventilate the work area before resuming service e Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers 1 Connect an R 134a refrigerant recovery recycling charging station A to the high pressure service port B and the low pressure service port C as shown following the equipment manufacturer s instructions Pressure Service Port Courtesy of AMERICAN HONDA MOTOR CO INC 2 Evacuate the system see SYSTEM EVACUATION 3 Add the same amount of new refrigerant oil to the system that was removed during recovery Use only DENSO ND OIL 8 refrigerant oil 4 Charge the system with the specified amount of R 134a refrigerant Do not overcharge the system the A C compressor will be damaged Select the appropriate units of measure for your refrigerant charging station 2008 Acura MDX 2007 09 HVAC Climate Control MDX Refrigerant Capacity 600 to 650 g 0 60 to 0 65 kg 1 32 to 1 43 Ibs 21 2 to 22 9 oz 5 Check for refrigerant leaks see REFRIGERANT LEAK TEST 6 Check the system performance see A C SYSTEM TEST REFRIGERANT LEAK TEST SPECIAL TO
28. sce FRONT MODE CONTROL MOTOR TEST Is the front mode control motor OK YES Go to step 7 NO Replace the front mode control motor see FRONT MODE CONTROL MOTOR REPLACEMENT 7 Disconnect the front mode control motor 7P connector Disconnect climate control unit connector A 40P Check for continuity between the following terminals of climate control unit connector A 40P and the front mode control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals FRONT MODE CONTROL MOTOR 7P CONNECTOR Wire side of female terminals 10 11 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 80 Identifying Continuity Between Climate Control Unit A 40P And Front Mode Control Motor 7P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the front mode control motor Check for continuity between body ground and climate control unit connector A 40P No 31 32 33 and 34 terminals individually CLIMATE CONTROL UNIT CONNECTOR A 40P annnnnan nmnnnnmnryar 74 WHT Wire side of female terminals Fig 81 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 40P No 31 32 33 And 34 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there contin
29. 09 HVAC Climate Control MDX 23 24 25 26 27 28 A C CONDENSER FAN 2P CONNECTOR BLU L Wire side of female terminals Fig 145 Measuring Voltage Between A C Condenser Fan 2P Connector No 2 Terminal And Bod Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Go to step 23 NO Repair open in the wire between the A C condenser fan relay and the A C condenser fan Set the A C button and fan control button OFF then turn the ignition switch to LOCK 0 Reconnect the A C condenser fan 2P connector Connect the A C condenser fan 2P connector No 1 terminal to body ground with a jumper wire A C CONDENSER FAN 2P CONNECTOR RED JUMPER WIRE Wire side of female terminals Fig 146 Identifying A C Condenser Fan 2P Connector No 1 Terminal To Body Ground Courtesy of AMERICAN HONDA MOTOR INC Turn the ignition switch to ON ID then set the A C button and fan control button ON Does the A C condenser fan run at high speed YES Go to step 27 NO Replace the A C condenser fan motor see RADIATOR AND FAN REPLACEMENT Set the A C button and fan control button OFF then turn the ignition switch to LOCK 0 Disconnect the jumper wire 2008 Acura MDX 2007 09 HVAC Climate Control MDX 29 30 31 32 33 34 Remove the fan control relay from the relay block and test it see RELAY CONTROL MODULE TEST Is the relay OK YES G
30. A 40P And Front Mode Control Motor 7P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the front mode control motor Check for continuity between body ground and climate control unit connector A 40P No 16 and No 17 terminals individually 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR 40 e Teo Te o Ts ao 24 25 20 27 m 39 ov 3 o s e or Wire side of female terminals Fig 84 Identifvine Continuity Between Body Ground And Climate Control Unit Connector A 40P No 16 And No 17 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the front mode control motor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1241 OR DTC INDICATOR C A PROBLEM IN THE FRONT BLOWER MOTOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B1241 or C indicated
31. A short in the in car Climate control unit Signal error temperature sensor circuit A short in the outside Climate control unit Signal error temperature sensor circuit An open in the sunlight Climate control unit Signal error sensor circuit A short in the sunlight Climate control unit Signal error sensor circuit An open in the front Climate control unit Signal error evaporator temperature sensor circuit B1232 A short in the front Climate control unit Signal error An open in the outside air Climate control unit Signal error temperature sensor circuit B1207 B1213 B1214 B1215 B1223 1 1225 An open in the in car Climate control unit Signal error temperature sensor circuit B1226 i B1227 B1228 B1229 B1230 B1231 2008 Acura MDX 2007 09 HVAC Climate Control MDX evaporator temperature sensor circuit B1233 An open in the driver s air Climate control unit Signal error mix control motor circuit A short in the driver s air Climate control unit Signal error mix control motor circuit A problem in the drivers Climate control unit Signal error air mix control linkage door or motor circuit An open in the passenger s Climate control unit Signal error air mix control motor circuit A short in the passenger s Climate control unit Signal error air mix control motor circuit A problem in the Climate control unit Signal error passenger s air mix control linkage door or motor circu
32. CAR TEMPERATURE SENSOR CONNECTOR Wire side of female termina s Fig 110 Identifying Continuity Between Climate Control Unit A 40P And Humidity In Car Temperature Sensor 4P Connector Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P and at the humidity in car temperature sensor 4P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate 2008 Acura MDX 2007 09 HVAC Climate Control MDX control unit NO Repair open in the wire s between the climate control unit and the humidity sensor DTC B2968 OR DTC INDICATOR A AND WINDSHIELD DEFROST A SHORT IN THE HUMIDITY SENSOR CIRCUIT 1 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B2968 or A and WINDSHIELD DEFROST indicated YES Go to step 5 NO Intermittent failure Check for DTCs Are these DTCs also present B1234 or K and AUTO and or B1237 or N and AUTO and or B1245 or G and or B2980 or B and WINDSHIELD DEFROST YES Go to step 13 NO Go to step 6 Turn the ignition switch to LOCK
33. DEFROSTER DOOR HEAT VENT DOOR gt HEAT DEF DEF 17 Identifying Climate Control Door Positions Courtesy of AMERICAN HONDA MOTOR INC Fi DUAL AIR MIX CONTROL SYSTEM 2008 Acura MDX 2007 09 HVAC Climate Control MDX DRIVER S AIR MIX DOOR Driver s side HOT ck Passenger s side COOL TE Fig 18 Identifying Dual Air Mix Control System Courtesy of AMERICAN HONDA MOTOR INC I DUAL AND I TRI CLIMATE CONTROL SYSTEM WITH NAVIGATION SYSTEM The i Dual climate control system automatically controls the temperature and the vent mode of the air direction to the driver s and passenger s side depending on the angle of the sun and the direction of the vehicle It calculates information such as date time longitude and latitude from the navigation system as well as the radiant strength of the sun from the sunlight sensor to determine the appropriate mode position and temperature to be directed to each side The i Tri climate control system is an addition of the automatic controls with the temperature and the vent mode of the air direction to the rear section to the i Dual climate control system 2008 Acura MDX 2007 09 HVAC Climate Control MDX A gt c EN SUNLIGHT SENSOR 2 AN gt poe SYSTEM DATE LONGITUDE LATITUDE DIRECTION OF THE VEHICLE IRRADIATE STRENGT
34. HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B1246 or H indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the rear air mix control motor circuit 10 2008 Acura MDX 2007 09 HVAC Climate Control MDX Turn the ignition switch to LOCK 0 Test the rear air mix control motor sce REAR AIR MIX CONTROL MOTOR TEST Is the rear air mix control motor OK YES Go to step 7 NO Replace the rear air mix control motor see REAR AIR MIX CONTROL MOTOR TEST or repair the rear air mix control linkage or door Disconnect the rear air mix control motor 7P connector Disconnect climate control unit connector B 14P Check for continuity between the following terminals of climate control unit connector B 14P and the rear air mix control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR B 14 Wire side of female terminals GRN K Hels Asid PNK _ REAR AIR MIX CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 103 Identifying Continuity Between Climate Control Unit B 14P And Rear Air Mix Control Motor 7P Connector Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the rear air mix control motor Check for continuity between body ground and climate control unit connector B 14
35. MDX 25 mm 2 2 kgf m 16 2 Ibf ft 3 Fig 209 Identifying Mounting Bolts And A C Compressor With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 9 Install the A C compressor in the reverse order of removal and note these items Inspect the A C lines for any signs of contamination If you re installing a new A C compressor you must calculate the amount of refrigerant oil to be removed from it see A C REFRIGERANT OIL REPLACEMENT A new A C compressor comes with a full charge of oil Replace the O rings with new ones at each fitting and apply a thin coat of refrigerant oil before installing them Be sure to use the correct O rings for HFC 134a R 134a to avoid leakage Use refrigerant oil DENSO ND OIL 8 for HFC 134a DENSO piston type A C compressor only To avoid contamination do not return the oil to the container once dispensed and never mix it with other refrigerant oils Immediately after using the oil reinstall the cap on the container and seal it to avoid moisture absorption Do not spill the refrigerant oil on the vehicle it may damage the paint if the refrigerant oil contacts the paint wash it off immediately Be careful not to damage the radiator fins when installing the compressor and the A C condenser fan shroud Charge the system see SYSTEM CHARGING A C COMPRESSOR CLUTCH CHECK 1 Check the pressure plate for discoloration peeling or other damage If there is damage
36. MOTOR CO INC When the engine is cool drain the engine coolant from the radiator see COOLANT CHECK Remove the clamp A Slide the hose clamps B back Remove the nut and the water valve C then disconnect the inlet heater hose D and the outlet heater hose E from the heater unit Engine coolant will run out when the hoses are disconnected drain it into a clean drip pan Be sure not to let coolant spill on the electrical parts or the painted surfaces If any coolant spills rinse it off immediately Fig 195 Identifying Clamp Slide Hose Clamps Water Valve Heater Hose And Outlet Heater Hose Nut With Torque Specification Courtesy of AMERICAN HONDA MOTOR INC Remove the mounting nuts from the heater unit Take care not to damage or bend the fuel lines or brake lines etc 2008 Acura MDX 2007 09 HVAC Climate Control MDX 1 3 kgf m 9 0 Ibf ft Fig 196 Identifying Heater Unit Mounting Nuts With Torque Specification Courtesy of AMERICAN HONDA MOTOR INC 7 Remove the dashboard see DASHBOARD REPLACEMENT 8 Disconnect the connector A from the front blower motor Remove the wire harness clips B Fig 197 Identifying Front Blower Motor Connector And Harness Clips Courtesy of AMERICAN HONDA MOTOR INC 9 Disconnect the connector A from the adaptive front lighting control unit then remove the harness clip B 2008 Acura MDX 2007 09 HVAC Climate Con
37. Max Cool If it doesn t reverse the connections the passenger s air mix control motor should run and stop at Max Hot When the passenger s air mix control motor stops running disconnect battery power immediately PASSENGER S AIR MIX CONTROL MOTOR Fig 174 Identifying Passenger s Air Mix Control Motor Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC 3 If the passenger s air mix control motor did not run in step 2 remove it then check the passenger s air mix 2008 Acura MDX 2007 09 HVAC Climate Control MDX control linkage and door for smooth movement e If the linkage and door move smoothly replace the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR REPLACEMENT e If the linkage or door sticks or binds repair them as needed e If the passenger s air mix control motor runs smoothly go to step 4 4 Measure the resistance between the No 5 and No 7 terminals It should be between 4 2 to 7 8 k ohms 5 Reconnect the passenger s air mix control motor 7P connector then turn the ignition switch to ON II 6 Using the backprobe set measure the voltage between the No 3 and No 5 terminals Max Cool about 1 5 V Max Hot about 4 5 V 7 If either the resistance or voltage readings are not as specified replace the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR REPLACEMENT PASSENGER S AIR MIX CONTROL MOTOR REPLACEMENT 1 Remove the glove
38. No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX 16 ive 18 19 Is there continuity YES Repair short to body ground in the wire NO Go to step 16 Turn the ignition switch to ON II and check the same terminal for voltage to body ground CLIMATE CONTROL UNIT CONNECTOR 40P Wire side of female terminals Fig 115 Identifvine Same Terminal For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there any voltage YES Repair short to power in the wire This short may have also damaged the climate control unit Repair the short to power before replacing the climate control unit NO Go to step 17 Turn the ignition switch to LOCK 0 Reconnect the climate control unit connector 40P Turn the ignition switch to ON and measure the voltage between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 116 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX Is there about 5 V YES Go to step 20 NO Check for a loose wire or poor connection at climate control unit connector A 40P If the connection is good substitute a known good clim
39. SENSOR 2P CONNECTOR Wire side of female terminals Fig 56 Identifvine Continuity Between No 24 And Front Evaporator Temperature Sensor 2P Connector No 2 Terminal Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 9 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Repair open in the wire between the climate control unit and the front evaporator temperature sensor Check for continuity between climate control unit connector A 40P No 8 terminal and the front evaporator temperature sensor 2P connector No 1 terminal CLIMATE CONTROL UNIT CONNECTOR A 40 Wire side of female terminals RED i 1 2 5 15 To v va i6 RED FRONT EVAPORATOR TEMPERATURE SENSOR 2P CONNECTOR Wire side of female terminals Fig 57 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And No 1 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P and at the front evaporator temperature sensor 2P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire between the climate control unit and the front evaporator temperature sensor
40. apply a thin coat of refrigerant oil before installing it 7 Remove the plug and install and tighten the relief valve 8 Charge the system see SYSTEM CHARGING A C CONDENSER REPLACEMENT 1 Recover the refrigerant with a recovery recycling charging station see REFRIGERANT RECOVERY 2 Remove the front bumper see FRONT BUMPER REMOVAL INSTALLATION 3 Remove the bolt then disconnect the discharge hose A from the A C condenser 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft Fig 218 Identifying A C Condenser Discharge Hose Bolt With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 4 Remove the bolt then disconnect the front receiver line A from the A C condenser 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 219 Identifying A C Condenser Front Receiver Line With Bolt With Torque Specification Courtesy of AMERICAN HONDA MOTOR INC 5 Remove the bolts nut and the ATF cooler bracket A 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft Fig 220 Identifying ATF Cooler Bracket Nut And Bolts With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 6 Loosen the bolts then remove the A C condenser upper mount brackets A 2008 Acura MDX 2007 09 HVAC Climate Control MDX 9 8 1 0 kgf m 7 2 Ibf ft Fig 221 Identifvine A C Condenser Upper Mount Brackets Bolts With Torque Specification Courtesy of AMERICAN HONDA MOTOR
41. blower motor relay and body ground If the wire is OK check for poor ground at G202 see GROUND TO COMPONENTS INDEX DTC B1244 OR DTC INDICATOR F AN OPEN IN THE REAR AIR MIX CONTROL MOTOR CIRCUIT 2008 Acura MDX 2007 09 HVAC Climate Control MDX 1 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1244 or F indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the rear air mix control motor circuit Tur the ignition switch to LOCK 0 Test the rear air mix control motor see REAR AIR MIX CONTROL MOTOR TEST Is the rear air mix control motor OK YES Go to step 7 NO Replace the rear air mix control motor see REAR AIR MIX CONTROL MOTOR TEST 7 Disconnect the rear air mix control motor 7P connector Disconnect climate control unit connector A 40P and B 14P Check for continuity between the following terminals of climate control unit connector A 40P B 14P and the rear air mix control motor 7P connector 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 Wire side of female terminals Ln oi BABE ps see De
42. make sure the motor runs smoothly RECIRCULATION CONTROL MOTOR TEST NOTE Before testing check for HVAC DTCs see GENERAL TROUBLESHOOTING INFORMATION 1 Disconnect the 7P connector from the recirculation control motor NOTE Incorrectly applying power and ground to the recirculation control motor will damage it Follow the instructions carefully 2 Connect battery power to the No 1 terminal of the recirculation control motor and ground the No 2 terminal the recirculation control motor should run smoothly and stop at Fresh If it doesn t reverse the connections the recirculation control motor should run smoothly and stop at Recirculate When the recirculation control motor stops running disconnect battery power immediately 2008 Acura MDX 2007 09 HVAC Climate Control MDX RECIRCULATION CONTROL MOTOR Fig 178 Identifying Recirculation Control Motor Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC If the recirculation control motor did not run in step 2 remove it then check the recirculation control linkage and door for smooth movement e If the linkage and door move smoothly replace the recirculation control motor see RECIRCULATION CONTROL MOTOR REPLACEMENT e If the linkage or door stick or bind repair them as needed e If the recirculation control motor runs smoothly go to step 4 Usea digital multimeter with an output of 1 mA or less at the 20 kohms range With the recirc
43. mix control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals DRIVER S AIR MIX CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 68 Identifying Continuity Between Climate Control Unit A 40P And Driver s Air Mix Control Motor 7P Connector Terminal Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the driver s air mix control motor Check for continuity between body ground and climate control unit connector A 40P No 12 and No 13 terminals individually 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 69 Identifvine Continuity Between Body Ground And Climate Control Unit Connector A 40P No 12 And No 13 Terminals Courtesy of AMERICAN HONDA MOTOR INC CLIMATE CONTROL UNIT CONNECTOR A 40 PNK LTBLU 0 18 sa n sa m o v o uo s ss e os 29 e e Te TT T v Wire side of female terminals Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the driver s air mix control motor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1236 OR DTC INDICATOR M AND AUTO AN OPEN IN THE PASSENGER S AIR MIX C
44. replace the clutch set see A C COMPRESSOR CLUTCH OVERHAUL 2008 Acura MDX 2007 09 HVAC Climate Control MDX 2 Check the pulley bearing play and drag by rotating the pulley by hand Replace the clutch set with a new one if it is noisy or has excessive play drag see A C COMPRESSOR CLUTCH OVERHAUL Fig 210 Identifying Bearing Play Courtesy of AMERICAN HONDA MOTOR INC 3 Measure the clearance between the pulley A and the pressure plate B all the way around If the clearance is not within specified limits remove the pressure plate see COMPRESSOR CLUTCH OVERHAUL and add or remove shims as needed to increase or decrease clearance Clearance 0 30 0 60 mm 0 012 0 024 in NOTE The shims are available in three thicknesses 0 1 mm 0 3 mm and 0 5 mm Fig 211 Measuring Clearance Between Pulley And Pressure Plate Courtesy of AMERICAN HONDA MOTOR CO INC 4 Measure the resistance of the field coil If the resistance is not within specifications replace the field coil see A C COMPRESSOR CLUTCH OVERHAUL 2008 Acura MDX 2007 09 HVAC Climate Control MDX Field Coil Resistance 3 9 4 3 at 68 F 20 Fig 212 Measuring Resistance Of Field Coil Courtesy of AMERICAN HONDA MOTOR CO INC A C COMPRESSOR CLUTCH OVERHAUL Special Tools Required A C clutch holder Robin air 10204 or Kent Moore J37872 or Honda Tool and Equipment KMT J33939 commercially available R
45. see DTC B1238 or DTC indicator P and AUTO A Problem in the Passenger s Air Mix Control Linkage Door or Motor Circuit Climate control unit lost communication with gauge control module ECT message see DTC B1205 Climate Control Unit Lost Communication with Gauge Control Module VSP NE message DTC B1206 or DTC indicator AUTO Climate Control Unit Lost Communication with Gauge Control Module ECT message DTC B1207 Climate Control Unit Lost Communication with Gauge Control Module ILLUMI message An open or short in the front mode control motor circuit see DTC B1239 or DTC indicator A An Open or Short in the Front Mode Control Motor Circuit A problem in the front mode control linkage doors or motor circuit see DTC B1240 or DTC indicator B A Problem in the Front Mode Control Linkage Doors or Motor Circuit A problem in the front blower motor circuit see DTC B1241 or DTC indicator C A Problem in the Front Blower Motor Circuit An open in the rear air mix control motor circuit see DTC B1244 or DTC indicator F An Open in the Rear Air Mix Control Motor Circuit A short in the rear air mix control motor circuit see DTC B1245 or DTC indicator G A Short in the Rear Air Mix Control Motor Circuit A problem in the rear air mix control linkage door or motor circuit see DTC B1246 or DTC indicator H A Problem in the Rear Air Mix 2008 Acura MDX 2007 09 HVAC Climate Control MDX Control Linkage Door or Motor C
46. the recovery process 1s completed Be sure to put the same amount of new refrigerant oil back into the A C system before charging SYSTEM EVACUATION CAUTION e Air conditioning refrigerant or lubricant vapor can irritate your eyes nose or throat Be careful when connecting service equipment e Do not breathe refrigerant or vapor NOTE 2008 Acura MDX 2007 09 HVAC Climate Control MDX e If accidental system discharge occurs ventilate the work area before resuming service e Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers 1 When an A C System has been opened to the atmosphere such as during installation or repair it must be evacuated using an R 134a refrigerant recovery recycling charging station If the system has been open for several days the receiver dryer should be replaced and the system should be evacuated for several hours 2 Connect an R 134a refrigerant recovery recycling charging station A to the high pressure service port B and the low pressure service port C as shown following the equipment manufacturer s instructions Evacuate the system Pressure Service Port Courtesy of AMERICAN HONDA MOTOR CO INC 3 If the low pressure does not reach more than 93 3 kPa 700 mmHg 27 6 in Hg in 15 minutes there is probably a leak in the system Partially charge the system and check for leaks see step 3 on REFRIGERANT LEAK TEST
47. the symptom indication goes away replace the original audio unit REAR MODE CONTROL MOTOR CIRCUIT TROUBLESHOOTING 1 Check the No 30 10 A fuse in the under dash fuse relay box Is the fuse OK YES Go to step 2 NO Replace the fuse and recheck If the fuse blows again check for a short in the No 30 10 A fuse circuit 2 Disconnect the rear mode control motor 7P connector 3 Turn the ignition switch to ON II 2008 Acura MDX 2007 09 HVAC Climate Control MDX 4 Measure the voltage between the rear mode control motor 7P connector No 1 terminal and body ground REAR MODE CONTROL MOTOR 7P CONNECTOR T Wire side of female terminals Fig 134 Measuring Voltage Between Rear Mode Control Motor 7P Connector No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Go to step 5 NO Repair open in the wire between the No 30 10 A fuse in the under dash fuse relay box and the rear mode control motor 5 Turn the ignition switch to LOCK 0 6 Testthe rear mode control motor see REAR MODE CONTROL MOTOR TEST Is the rear mode control motor OK YES Go to step 7 NO Replace the rear mode control motor see REAR MODE CONTROL MOTOR TEST or repair the rear mode control linkage or door 7 Disconnect climate control unit connector B 14P 8 Check for continuity between body ground and climate control unit connector B 14P No 3 and No
48. valve High and low pressures are equalized as soon as the A C compressor is stopped and both gauges fluctuate while running Foreign particle stuck in high pressure valve Clogged A C condenser or Reduced airflow through A C radiator fins condenser A C condenser or radiator fan not working properly Recover evacuate and recharge with specified amount Replace the A C compressor e Clean e Check voltage and fan rpm e Check fan direction Low pressure hose and metal Clogged or kinked fittings are cooler than low pressure hose evaporator parts Temperature around expansion valve is too low compared with that around receiver dryer A C compressor clutch is dirty A C compressor bolt s are dirty A C compressor gasket is wet with oil Clogged high pressure line A C compressor shaft seal leaking Leaking around bolt s A C fitting is dirty Leaking O ring Repair or replace Repair or replace Replace the A C compressor Tighten bolt s or replace A C compressor Gasket leaking Replace the A C compressor Clean the A C fitting and replace the O ring
49. 09 HVAC Climate Control MDX PNK In 4 _ Wire side of female terminals Fig 41 Measuring Voltage Between Rear Blower Motor Relay 4P Socket No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Go to step 30 NO Repair open in the wire between the No 2 RR BLOWER 30 A in the under hood fuse box and the rear blower motor relay 30 Turn the ignition switch to ON II 3 Measure the voltage between the rear blower motor relay 4P socket No 2 terminal and body ground REAR BLOWER MOTOR RELAY 4P SOCKET ar 3 4 2 V L Wire side of female terminals Fig 42 Measuring Voltage Between Rear Blower Motor Relay 4P Socket No 2 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Go to step 32 NO Repair open in the wire between the No 30 10 A fuse in the under dash fuse relay box and the rear blower motor relay 32 Turn the ignition switch to LOCK 0 33 Check for continuity between the rear blower motor relay 4P socket No 4 terminal and body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX REAR BLOWER MOTOR RELAY 4P SOCKET Wire side of female terminals Fig 43 Identifying Continuity Between Rear Blower Motor Relay 4P Socket No 4 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair open in the GRY wire betwee
50. 2P Connector No 1 Terminal And Bod Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Replace the radiator fan motor see RADIATOR AND FAN REPLACEMENT NO Check for an open in the wire between the radiator fan and body ground If the wire is OK check for poor ground at G301 see GROUND TO COMPONENTS INDEX Turn the ignition switch to LOCK 0 Remove A C diode A from the relay block 38 39 40 2008 2007 09 HVAC Climate Control Using the diode setting on a DVOM check for current flow in both directions between the A C diode A No 1 and No 2 terminals A C DIODE A 12 65 22 Fig 150 Identifying Current Flow Both Directions Between A C Diode No 1 And No 2 Terminals Courtesy of AMERICAN HONDA MOTOR INC 15 there current flow in only one direction YES Go to step 39 NO Replace A C diode A Turn the ignition switch to ON II Measure the voltage between A C diode A 2P socket No 2 terminal and body ground A C DIODE A 2P SOCKET Fig 151 Measuring Voltage Between A C Diode 2P Socket No 2 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Replace the under hood fuse relay box see REMOVAL AND INSTALLATION NO Repair open in the wire between the No 30 10 A fuse in the under dash fuse relay box and A C diode A A C CONDENSER FAN HIGH SPEED CIRCUIT TROUBLESHOOTI
51. 4 terminals individually 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR 14 YEL BLK 1 2 cp 5 A e Ax sp i i Wire side of female terminals Fig 135 Identifying Continuity Between Body Ground And Climate Control Unit Connector B 14P No 3 And No 4 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the rear mode control motor NO Go to step 9 9 Turn the ignition switch to ON II and check the same terminals for voltage to body ground CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of female terminals Fig 136 Identifying Same Terminals For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there any voltage YES Repair short to power in the wire s between the climate control unit and the rear mode control motor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Go to step 10 10 Turn the ignition switch to LOCK 0 11 Check for continuity between the following terminals of climate control unit connector B 14P and the 2008 Acura MDX 2007 09 HVAC Climate Control MDX rear mode control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR 14 Wire side of female terminals REAR MODE CONTROL MOTOR
52. 40P Wire side of female terminals Fig 99 Identifying Continuity Between Climate Control Unit Connector 40 No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire NO Go to step 16 Turn the ignition switch to ON ID and check the same terminal for voltage to body ground 17 18 19 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 m o DIBCIGID D HEBDO Wire side of female terminals Fig 100 Identifying Same Terminal For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there any voltage YES Repair short to power in the wire This short may have also damaged the climate control unit Repair the short to power before replacing the climate control unit NO Go to step 17 Turn the ignition switch to LOCK 0 Reconnect the climate control unit connector 40P Turn the ignition switch to ON ID and measure the voltage between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 101 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there about 5 V YES Go to step 20 NO Check f
53. 4P socket No 1 terminal and body ground FRONT BLOWER MOTOR RELAY 4P SOCKET Fig 92 Measuring Voltage Between Front Blower Motor Relay 4P Socket No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Go to step 30 NO Replace the under hood fuse relay box see REMOVAL AND INSTALLATION Turn the ignition switch to ON II Measure the voltage between the front blower motor relay 4P socket No 4 terminal and body ground 32 33 2008 2007 09 HVAC Climate Control FRONT BLOWER MOTOR RELAY 4P SOCKET V i Fig 93 Measuring Voltage Between Front Blower Motor Relay 4P Socket No 4 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Go to step 32 NO Repair open in the wire between the No 30 10 A fuse in the under dash fuse relay box and the front blower motor relay Turn the ignition switch to LOCK 0 Check for continuity between the front blower motor relay 4P socket No 3 terminal and body ground FRONT BLOWER MOTOR RELAY 4P SOCKET 2 BLK Fig 94 Identifying Continuity Between Front Blower Motor Relay 4P Socket 3 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair open in the WHT wire between the front blower motor relay and the blower motor NO Check for an open in the wire between the front
54. 7P CONNECTOR Wire side of female terminals Fig 137 Identifying Continuity Between Climate Control Unit 14 And Rear Mode Control Motor 7P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector B 14P and at the rear mode control motor 7P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire s between the climate control unit and the rear mode control motor CLIMATE CONTROL UNIT TROUBLESHOOTING 1 Check the No 30 10 A fuse in the under dash fuse relay box Is the fuse OK YES Go to step 2 NO Replace the fuse and recheck If the fuse blows again check for a short in the No 30 10 A fuse circuit 2 Turn the ignition switch to ON 3 Measure the voltage between climate control unit connector A 40P No 3 terminal and body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 YEL Wire side of female terminals Fig 138 Measuring Voltage Between Climate Control Unit Connector A 40P No 3 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Go to step 4 NO Repair open in the wire between the
55. AGE TROUBLESHOOTING in cold weather INFORMATION NOTE e Blower motor operation It is normal for the blower s to run slowly until the engine coolant temperature begins to rise If the blower 2008 Acura MDX 2007 09 HVAC Climate Control MDX continues to run slowly for an abnormal length of time continue to troubleshoot the problem Check the coolant level see COOLANT CHECK Check the radiator cap see RADIATOR CAP TEST Check the operation of the air mix control motor and door see DRIVER S AIR MIX CONTROL MOTOR TEST 4 Check the coolant temperature Check the operation of the heater valve see HEATER VALVE CABLE ADJUSTMENT Check the blower motor unit for Insufficient heating obstructions Check for air leaks around the ducts and vents Check the inlet hose temperature SYSTEM DESCRIPTION e If itis COLD check for restrictions in the hose a damaged or leaking thermostat and a damaged or leaking water pump If it is HOT check for restrictions in the heater core Back flush the heater core using standard commercially available equipment or replace the heater core Damaged cylinder head gasket The air conditioning system removes heat from the passenger compartment by transferring heat from the ambient air to the evaporator The evaporator cools the air with the refrigerant that is circulating through the evaporator The refrigerant expands in the evapor
56. B2980 or B and WINDSHIELD DEFROST YES Go to step 13 NO Go to step 6 6 Turn the ignition switch to LOCK 0 7 Test the rear air mix control motor sce REAR AIR MIX CONTROL MOTOR TEST Is the rear air mix control motor OK YES Go to step 8 NO Replace the rear air mix control motor see REAR AIR MIX CONTROL MOTOR TEST 8 Disconnect the rear air mix control motor 7P connector 9 Disconnect climate control unit connector A 40P and B HP 10 Check for continuity between climate control unit connector B 14P No 5 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of female terminals Fig 96 Identifvine Continuity Between Climate Control Unit Connector B 14P No 5 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the rear air mix control motor NO Go to step 11 11 Check for continuity between climate control unit connector A 40P No 6 terminal and climate control 2008 Acura MDX 2007 09 HVAC Climate Control MDX unit connector B 14P No 5 terminal CLIMATE CONTROL UNIT CONNECTOR A 40 Wire side of female terminals GRY 2 T JPE CLIMATE CONTROL UNIT CONNECTOR 14 Wire side of female terminals Fig 97 Identifying Continuity Between Climate Control Unit Connector A 40P N
57. Between Under Dash Fuse Relay Box Connector X 39P No 27 And No 4 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires and poor connections at climate control unit connector A 40P If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire between the MICU and the climate control unit RADIATOR AND A C CONDENSER FAN LOW SPEED CIRCUIT TROUBLESHOOTING NOTE e Do notuse this troubleshooting procedure if the A C compressor is inoperative Refer to the SYMPTOM TROUBLESHOOTING INDEX Before performing symptom troubleshooting check for powertrain DTCs see GENERAL TROUBLESHOOTING INFORMATION 1 Check the No 15 30 A fuse in the relay block and the No 30 10 A fuse in the under dash fuse relay Oe 7 2008 2007 09 HVAC Climate Control box Are the fuses OK YES Go to step 2 NO Replace the fuse s and recheck If the fuse s blow again check for a short in the No 15 30 A and No 30 10 A fuse s circuit Remove the A C condenser fan relay from the relay block and test it see POWER RELAY TEST 1 the relay OK YES Go to step 3 NO Replace the A C condenser fan relay Connect the HDS to the DLC Turn the ignition switch to ON ID Turn on the A C Check the FAN
58. C Climate Control MDX 27 YEL HUMIDITY SENSOR OUTPUT 28 OUTSIDE AIR TEMPERATURE SENSOR OUTPUT 29 SUNLIGHT SENSOR OUTPUT 30 E AIR MIX POTENTIAL INPUT WHT MODE CONTROL MODE 1 OUTPUT FRONT MODE CONTROL MODE 2 PNK PUR BLU OUTPUT RONT MODE CONTROL MODE 3 OUTPUT RONT MODE CONTROL MODE 4 BLK BLK GRN OUTPUT W RECIRCULATION CONTROL MODE 1 OUTPUT RE ERE CONTROL MODE 2 OUTPUT 37 GROUND G506 OUTPUT 38 RECIRCULATION CONTROL MODE 3 1 With navigation system FRONT MODE CONTROL MODE3 OUTPUT FRONT MODE CONTROL MODE 4 OUTPUT OUTPUT CLIMATE CONTROL UNIT INPUTS AND OUTPUTS CLIMATE CONTROL UNIT CONNECTOR 14 Wire side of female terminals Fig 21 Identifying Climate Control Unit Connector B 14P Terminals Courtesy of AMERICAN HONDA MOTOR INC CONNECTOR B CLIMATE CONTROL UNIT INPUTS AND OUTPUTS CONNECTOR B Signal GRN PNK YEL BLK REAR MODE VENT INPUT PUR REAR AIR MIX POTENTIAL INPUT 6 LTBLU REAR EVAPORATOR TEMPERATURE SENSOR OUTPUT 8 BLU AUDIO UNIT HVAC BUS INPUT OUTPUT ORN REAR CLIMATE CONTROL PANEL A C BUS RX INPUT OUTPUT 12 REAR CLIMATE CONTROL PANEL A C BUS TX INPUT OUTPUT 2008 Acura MDX 2007 09 HVAC Climate Control MDX 13 RED REAR BLOWER FEEDBACK INPUT BLU POWER TRANSISTOR CONTROL OUTPUT REAR CLIMATE CONTROL UNIT INPUTS AND OUTPUTS REAR CLIMATE CONTROL PANEL 10P CONNECTOR
59. Continuity Between Climate Control Unit A 40P And Navigation Unit Connector A 20P Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 9 NO Repair open in the wire s between the climate control unit and the navigation unit 9 Check for continuity between body ground and navigation unit connector A 20P No 4 14 and 15 terminals individually NAVIGATION UNIT CONNECTOR 20 Wire side of female terminals Fig 129 Identifvine Continuity Between Body Ground And Navigation Unit Connector A 20P No 4 14 And 15 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the navigation unit 10 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Go to step 10 Check for continuity between navigation unit connector A 20P terminals as follows TERMINALS REFERENCE CHART 4 14 15 14 15 15 there continuity between any of the terminals YES Repair the short in the wires NO Substitute a known good navigation unit and recheck If the symptom goes away replace the original navigation unit If the symptom remains substitute a known good climate control unit and recheck If the symptom goes away replace the original climate control unit DTC B2983 OR DTC INDICATOR K A PROBLEM IN THE RECIRCULATION CONTROL LINKAGE DOOR OR MOTOR CIRCUIT 1
60. D CIRCUIT see the A C TROUBLESHOOTING p ep NM IROUBLESHOOTING COMPONENTS INDEX e Cleanliness and tightness of all terminals The A C condenser fan does not run at high speed but both fans run at low speed and the A C compressor operates with the A C on Both fans do not run at high speed with the A C on but both fans run at low speed and the A C compressor operates with the A C on A C condenser fan high speed circuit HL DE GENERAL troubleshooting see A C CONDENSER INFORMATION FAN HIGH SPEED CIRCUIT MERETUR TROUBLESHOOTING Cleanliness and tightness of all terminals ECT troubleshooting ECT sensor 2 circuit Powertrain DTCs see low voltage see DTC P2184 ECT GENERAL SENSOR 2 CIRCUIT LOW TROUBLESHOOTING VOLTAGE ECT sensor 2 circuit high INFORMATION voltage see DTC P2185 ECT SENSOR Cleanliness and tightness of all 2 CIRCUIT HIGH VOLTAGE terminals HVAC DTCs see GENERAL TROUBLESHOOTING INFORMATION The A C compressor A C compressor clutch circuit Blown fuse No 17 7 5 A in the relay block and No 30 10 A in the under dash fuse relay box Blower motor operation Cleanliness and tightness of all terminals ECT troubleshooting ECT sensor 2 circuit low voltage see DTC P2184 ECT SENSOR 2 CIRCUIT LOW VOLTAGE ECT sensor 2 circuit high e Powertrain DTCs see Blower fan s runs voltage see DTC P2185 ECT SENSOR GENERAL slower than expected 2 CIRCUIT HIGH VOLT
61. ENSOR TEST Is the outside air temperature sensor OK YES Go to step 7 NO Replace the outside air temperature sensor 7 Disconnect climate control unit connector A 40P Check for continuity between climate control unit connector A 40P No 28 terminal and the outside air temperature sensor 2P connector No 2 terminal CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals LH Te I 1 7 702017741 E EA OUTSIDE AIR TEMPERATURE SENSOR 2 CONNECTOR Wire side of female terminals Fig 48 Identifying Continuity Between No 28 And Outside Air Temperature Sensor 2P Connector No 2 Terminal Courtesy of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX Is there continuity YES Go to step 9 NO Repair open in the wire between the climate control unit and the outside air temperature sensor Check for continuity between climate control unit connector A 40P No 8 terminal and the outside air temperature sensor 2P connector terminal No 1 CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals IRED annnnpnnpmnmanmnm ra spe omo er n Toe T wu o 7 OUTSIDE AIR TEMPERATURE SENSOR 2P CONNECTOR Wire side of female terminals Fig 49 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And Terminal No 1 Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES
62. EVAPORATOR TEMPERATURE SENSOR 2P CONNECTOR Wire side of female terminals RED Fig 28 Identifying Continuity Between No 8 And Rear Evaporator Temperature Sensor 2P Connector No 1 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P B 14P and at the rear evaporator temperature sensor 2P connector If the connections are good substitute a known 2008 Acura MDX 2007 09 HVAC Climate Control MDX good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire between the climate control unit and the rear evaporator temperature sensor DTC B1214 OR DTC INDICATOR P A SHORT IN THE REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B1214 or P indicated YES Go to step 5 NO Intermittent failure 5 Turn the ignition switch to LOCK 0 6 Remove the rear evaporator temperature sensor see REAR EVAPORATOR TEMPERATURE SENSOR TEST and test it see REAR EVAPORATOR TEMPERATURE SENSOR TEST Is the rear evaporator temperature sen
63. H REAR CLIMATE id ad CONTROL PANEL CLIMATE CONTROL UNIT With i Tri FRONT DUAL AIR MIX CONTROL REAR AIR MIX CONTROL REAR AIR MIX DOOR PASSENGER S AIR MIX DOOR Fig 19 Identifying I Dual And I Tri Climate Control System Courtesy of AMERICAN HONDA MOTOR CO INC In the event that the navigation system malfunctions or when driving in areas where the navigation system cannot determine the vehicle position non coverage areas tunnels etc the climate control system will operate the same as a vehicle without a navigation system CLIMATE CONTROL UNIT INPUTS AND OUTPUTS 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40P e n z ree 0 ee A Wire side of female terminals Fig 20 Identifying Climate Control Unit Connector A 40P Terminals Courtesy of AMERICAN HONDA MOTOR INC CONNECTOR A CLIMATE CONTROL UNIT INPUTS AND OUTPUTS CONNECTOR A Signal WHT BACKUP BLU FRONT BLOWER FEEDBACK INPUT RED PUR PNK YEL GRN FRONT MODE DEF OUTPUT ORN FRONT MODE VENT OUTPUT YEL OUTPUT ORN RECIRCULATE OUTPUT BLU NAVIGATION UNIT CLK OUTPUT RED NAVIGATION UNIT SO OUTPUT LTBLU ILLUMK INPUT 24 BRN FRONT EVAPORATOR TEMPERATURE SENSOR OUTPUT 25 PUR ACC INPUT LTGRN PRESSURE SENSOR OUTPUT 2008 Acura MDX 2007 09 HVA
64. HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P and at the passenger s air mix control motor 7P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire s between the climate control unit and the passenger s air mix control motor DTC B1237 OR DTC INDICATOR N AND AUTO A SHORT IN THE PASSENGER S AIR MIX 2008 Acura MDX 2007 09 HVAC Climate Control MDX CONTROL MOTOR CIRCUIT Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1237 or N and AUTO indicated YES Go to step 5 NO Intermittent failure Check for DTCs Are these DTCs also present B1234 or and AUTO and or B1245 or and or B2968 or A and WINDSHIELD DEFROST and or B2980 or B and WINDSHIELD DEFROST YES Go to step 13 NO Go to step 6 Turn the ignition switch to LOCK 0 Test the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR TEST Is the passenger s air mix control motor OK YES Go to step 8 NO Replace the passenger s air mix contro
65. INDICATOR B AND AUTO A SHORT IN THE IN CAR TEMPERATURE SENSOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B1226 or B and AUTO indicated YES Go to step 5 NO Intermittent failure 5 Turn the ignition switch to LOCK 0 6 Remove the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT and test it see HUMIDITY IN CAR TEMPERATURE SENSOR TEST Is the in car temperature sensor OK YES Go to step 7 NO Replace the humidity in car temperature sensor 7 Disconnect climate control unit connector A 40P 8 Check for continuity between climate control unit connector A 40P No 5 terminal and body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 46 Identifying Continuity Between Climate Control Unit Connector A 40P No 5 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the in car temperature sensor NO Go to step 9 9 Check for continuity between climate control unit connector A 40P
66. LOW CTRL in the PGM FI Data List with the HDS Is the FAN LOW CTRL on YES Go to step 7 NO Substitute a known good PCM see SUBSTITUTING THE PCM and retest If the symptom indication goes away with a known good PCM replace the original PCM see PCM REPLACEMENT Measure the voltage between the A C condenser fan relay 4P socket No 1 terminal and body ground A C CONDENSER FAN RELAY 4P SOCKET Y Fig 141 Measuring Voltage Between A C Condenser Fan Relay 4P Socket No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC 10 11 2008 Acura MDX 2007 09 HVAC Climate Control MDX Is there battery voltage YES Go to step 8 NO Replace the under hood fuse relay box see REMOVAL AND INSTALLATION Connect the A C condenser fan relay 4P socket No 1 and No 2 terminals with a jumper wire A C CONDENSER FAN RELAY 4P SOCKET Fig 142 Identifying A C Condenser Fan Relay 4P Socket No 1 And No 2 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Do the A C condenser and radiator fans run on low YES Go to step 9 NO Go to step 18 Disconnect the jumper wire Turn the ignition switch to ON II Measure the voltage between the A C condenser fan relay 4P socket No 4 terminal and body ground A C CONDENSER FAN RELAY 4P SOCKET I Fig 143 Measuring Voltage Between A C Condenser Fan Relay 4P Socket No 4 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR
67. MOTOR INC 15 there any voltage YES Repair short to power in the wire This short may have also damaged the climate control unit Repair the short to power before replacing the climate control unit NO Go to step 20 20 Turn the ignition switch to LOCK 0 2008 Acura MDX 2007 09 HVAC Climate Control MDX 21 Reconnect climate control unit connector 40P 22 Turn the ignition switch to ON and measure the voltage between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P 4 K Wire side of female terminals Fig 126 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there about 5 V YES Go to step 23 NO Check for a loose wire or poor connection at climate control unit connector A 40P If the connection is good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit 23 While checking the same terminal for voltage to ground reconnect these items individually and note the voltage reading each time e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor Humidity in car temperature sensor e A C pressure sensor CLIMATE CONTROL UNIT CONNECTOR A 40 annnn
68. NG 2008 Acura MDX 2007 09 HVAC Climate Control MDX NOTE e Do not use this troubleshooting procedure if the radiator fan and or the A C compressor is inoperative Refer to the SYMPTOM TROUBLESHOOTING INDEX Before doing any symptom troubleshooting check for powertrain DTCs see GENERAL TROUBLESHOOTING INFORMATION 1 Remove the fan control relay from the relay block and test it see RELAY CONTROL MODULE TEST Is the relay OK YES Go to step 2 NO Replace the fan control relay 2 Turn the ignition switch to ON II 3 Measure the voltage between the fan control relay 5P socket No 5 terminal and body ground FAN CONTROL RELAY SP SOCKET 9 Fig 152 Measuring Voltage Between Fan Control Relay 5P Socket No 5 Terminal And Bod Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Go to step 4 NO Replace the under hood fuse relay box see REMOVAL AND INSTALLATION 4 Turn the ignition switch to LOCK 0 5 Check for continuity between the fan control relay 5P socket No 2 terminal and body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX FAN CONTROL RELAY 5P SOCKET Q 4 Fig 153 Identifying Continuity Between Fan Control Relay 5P Socket No 2 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 6 NO Check for an open in the wire between the fan control relay and body g
69. No 30 10 A fuse in the under dash fuse relay box and the climate control unit 4 Turn the ignition switch to LOCK 0 5 Check for continuity between climate control unit connector A 40P No 37 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P T 9 Te e Tu T e Tm w 7T o 9 9 m 29 m m m e e m m m7 BLK hd Wire side of female terminals Fig 139 Identifying Continuity Between Climate Control Unit Connector A 40P No 37 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 6 NO Check for an open in the wire between the climate control unit and body ground If the wire is OK check for poor ground at G506 see GROUND TO COMPONENTS INDEX 6 Disconnect climate control unit connector A 40P 2008 Acura MDX 2007 09 HVAC Climate Control MDX 7 Disconnect under dash fuse relay box connector X 39P 8 Check for continuity between under dash fuse relay box connector X 39P No 27 terminal and climate control unit connector A 40P No 4 terminal UNDER DASH FUSE RELAY BOX CONNECTOR X Wire side of female terminals irae pa we 2 1 s TeTnTe Te Ts To Tuus 7T CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals Fig 140 Identifying Continuity
70. No 5 and No 8 terminals CLIMATE CONTROL UNIT CONNECTOR A 40P tTBLU RED I2 DO 2 2 2 m zr m m o we m e m Wire side of female terminals Fig 47 Identifvine Continuity Between Climate Control Unit Connector A 40P No 5 And No 8 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short in the wires between the climate control unit and the in car temperature sensor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1227 OR DTC INDICATOR C AND AUTO AN OPEN IN THE OUTSIDE AIR TEMPERATURE SENSOR CIRCUIT 2008 Acura MDX 2007 09 HVAC Climate Control MDX 1 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1227 or C and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the outside air temperature sensor circuit Tur the ignition switch to LOCK 0 Remove the outside air temperature sensor see OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT and test it see OUTSIDE AIR TEMPERATURE S
71. OLS REQUIRED Leak detector Honda Tool and Equipment YGK H 10PM or commercially available CAUTION e Air conditioning refrigerant or lubricant vapor can irritate your eyes nose or throat e Be careful when connecting service equipment e Do not breathe refrigerant or vapor NOTE e If accidental system discharge occurs ventilate the work area before resuming service e Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers 1 Connect an R 134a refrigerant recovery recycling charging station A to the high pressure service port B and the low pressure service port C as shown following the equipment manufacturer s instructions 2008 Acura MDX 2007 09 HVAC Climate Control MDX Pressure Service Port Courtesy of AMERICAN HONDA MOTOR INC 2 Open the high pressure valve to charge the system to the specified capacity then close the supply valve and disconnect the charging station fittings Select the appropriate units of measurement for your refrigerant charging station Refrigerant Capacity 600 to 650 g 0 60 to 0 65 kg 1 32 to 1 43 Ibs 21 2 to 22 9 oz 3 Check the system for leaks using an R 134a refrigerant leak detector with an accuracy of 14 g 0 5 oz per year or better 4 If you find leaks that require the system to be opened to repair or replace hoses fittings etc do the refrigerant recovery 5 After checking and repairing leaks the s
72. ONNECTOR Wire side of female terminals Fig 105 Measuring Voltage Between Rear Climate Control Panel 10P Connector No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Go to step 9 NO Repair open in the wire between the No 30 10 A fuse in the under dash fuse relay box and the rear climate control panel Tur the ignition switch to LOCK 0 10 Check for continuity between the rear climate control panel 10P connector No 3 terminal and body ground REAR CLIMATE CONTROL PANEL 10P CONNECTOR Wire side of female terminals Fig 106 Identifying Continuity Between Rear Climate Control Panel 10P Connector No 3 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 11 NO Check for an open in the wire between the rear climate control panel and body ground If the wire is OK check for poor ground at G506 see GROUND TO COMPONENTS INDEX 2008 Acura MDX 2007 09 HVAC Climate Control MDX 11 Disconnect climate control unit connector B 14P 12 Check for continuity between the following terminals of climate control unit connector B 14P and the 13 rear climate control panel connector CLIMATE CONTROL UNIT CONNECTOR 14 Wire side of female terminals ze OR ZITAT REAR CLIMATE CONTROL PANEL 10P CONNECTOR Wire side of female terminals Fig 107 Ide
73. ONTROL MOTOR CIRCUIT l 2 3 Clear the DTC with HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1236 or M and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the passenger s air mix control motor circuit Turn the ignition switch to LOCK 0 Test the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR TEST Is the passenger s air mix control motor OK 2008 Acura MDX 2007 09 HVAC Climate Control MDX YES Go to step 7 NO Replace the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR REPLACEMENT 7 Disconnect the passenger s air mix control motor 7P connector 8 Disconnect climate control unit connector A 40P 9 Check for continuity between the following terminals of climate control unit connector A 40P and the passenger s air mix control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals PASSENGER S AIR MIX CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 70 Identifying Continuity Between Climate Control Unit A 40P And Passenger s Air Mix Control Motor 7P Connector Terminals Courtesy of AMERICAN
74. OR INC HUMIDITY IN CAR TEMPERATURE SENSOR QUALITY The capacitance of the humidity sensor changes by the adsorption and the evaporation of moisture The resistance change of the humidity sensor changes the output voltage op ee Os EA VOLTAGE V 0 20 40 60 80 100 HUMIDITY LEVEL rh 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 14 Voltage Vs Humidity Level Graph Courtesy of AMERICAN HONDA MOTOR INC A C PRESSURE SENSOR The A C pressure sensor converts A C pressure into electrical signals to the PCM NOTE The pressures can be monitored using the HDS PGM FI Data List SENSOR UNIT Fig 15 Identifying A C Pressure Sensor Courtesy of AMERICAN HONDA MOTOR CO INC The response of the A C pressure sensor is shown in the graph NOTE When the refrigerant is below 196 kPa 2 0 kgf cm 28 psi or above 3 140 kPa 32 kgf cm 455 psi the PCM turns the compressor relay off to protect the A C compressor 2008 Acura MDX 2007 09 HVAC Climate Control MDX OUTPUT 4575 VOLTAGE Vout 0 684 0 425 0 2945 Ax O 99 0 196 3 138 kPa 1 2 32 kaf em 14 28 455 psi A C PRESSURE Fig 16 A C Pressure Sensor Graph Courtesy of AMERICAN HONDA MOTOR INC CLIMATE CONTROL DOOR POSITIONS 2008 Acura MDX 2007 09 HVAC Climate Control MDX
75. OR A 40P Wire side of female terminals RED Ls eT Te Io Te s To To Te To 7T n z m w a m m w e n v e e w aa RECIRCULATION CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 31 Identifying Continuity Between Climate Control Unit A 40P And Recirculation Control Motor 7P Connector Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the recirculation control motor 10 Check for continuity between body ground and climate control unit connector A 40P No 35 36 and 38 terminals individually CLIMATE CONTROL UNIT CONNECTOR A 40P LT Ts s Te ee TeTeTeTew L7 x s m o e w s wv Wire side of female terminals Fig 32 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 40P No 35 36 And 38 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the recirculation control motor 2008 Acura MDX 2007 09 HVAC Climate Control MDX 11 12 13 NO Go to step 11 Check for continuity between climate control unit connector A 40P terminals as follows TERMINALS REFERENCE CHART From terminal To terminals 35 36 38 36 38 Is there continuity between any of
76. OTOR PASSENGER S AIR MIX CONTROL MOTOR FRONT EVAPORATOR TEMPERATURE SENSOR CLIMATE CONTROL UNIT HUMIDITY IN CAR TEMPERATURE SENSOR FRONT POWER TRANSISTOR Fig 3 Identifying Climate Control Component Location 3 Of 3 Courtesy of AMERICAN HONDA MOTOR CO INC A C SERVICE TIPS AND PRECAUTIONS WARNING Compressed air mixed with the R 134a forms a combustible vapor e The vapor can burn or explode causing serious injury e Never use compressed air to pressure test R 134a service equipment or vehicle air conditioning systems CAUTION e Air conditioning refrigerant or lubricant vapor can irritate your eyes nose or throat Be careful when connecting service equipment e Do not breathe refrigerant or vapor 2008 Acura MDX 2007 09 HVAC Climate Control MDX The air conditioning system uses HFC 134a R 134a refrigerant and polyalkyleneglycol PAG refrigerant oil which are not compatible with CFC 12 R 12 refrigerant and mineral oil Do not use R 12 refrigerant or mineral oil in this system and do not attempt to use R 12 servicing equipment damage to the air conditioning system or your servicing equipment will result Use only service equipment that is U L listed and is certified to meet the requirements of SAE J2210 to remove R 134a from the air conditioning system If accidental system discharge occurs ventilate the work area before resuming service R 134a service equipment or vehicle air conditioning sy
77. Outlet of expansion valve is valve not frosted low pressure gauge indicates vacuum Moisture in system Frozen expansion valve Moisture in system Expansion valve is not frosted and low pressure line is not cold Low pressure gauge indicates vacuum Faulty expansion valve Recover evacuate see REFRIGERANT RECOVERY and recharge with specified amount see SYSTEM CHARGING e Clean e Check voltage and fan rpm e Check fan direction Restricted lines Replace the A C compressor Replace Recover evacuate and recharge with specified amount Recover evacuate and recharge with specified amount Replace the expansion valve Discharge temperature is low and the airflow from vents is restricted Frozen evaporator Clogged expansion Expansion valve is frosted valve Receiver dryer outlet is cool and inlet is warm should be Clogged receiver dryer warm during operation Run the fan with A C compressor off then check evaporator temperature sensor Clean or replace Replace Low pressure hose and service port are cooler than Expansion valve open Repair or replace 2008 Acura MDX 2007 09 HVAC Climate Control MDX Suction pressure abnormally high the temperature around evaporator too long Suction pressure is lowered when A C condenser is cooled by water Excessive refrigerant in system Faulty gasket Faulty high pressure
78. P No 1 and No 2 terminals individually 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of female terminals Fig 104 Identifying Continuity Between Body Ground And Climate Control Unit Connector B 14P No 1 And No 2 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the rear air mix control motor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B2965 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH REAR CLIMATE CONTROL PANEL 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS 4 Check for DTCs Is DTC B2965 indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the rear climate control panel and climate control unit circuit Turn the ignition switch to LOCK 0 Disconnect the rear climate panel 10P connector Turn the ignition switch to ON II Measure the voltage between the rear climate control panel 10P connector No 1 terminal and body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX REAR CLIMATE CONTROL PANEL 10P C
79. R MOTOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B1240 or B indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the mode control motor circuit 5 Turn the ignition switch to LOCK 0 2008 Acura MDX 2007 09 HVAC Climate Control MDX Test the front mode control motor see FRONT MODE CONTROL MOTOR TEST Is the front mode control motor OK YES Go to step 7 NO Replace the front mode control motor see FRONT MODE CONTROL MOTOR REPLACEMENT or repair the front mode control linkage or doors 7 Disconnect the front mode control motor 7P connector 10 Disconnect climate control unit connector A 40P Check for continuity between the following terminals of climate control unit connector A 40P and the front mode control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals ORN ETT Te Te Te Te Te Te Te 2 z 0 s s e o e e v e Q ORN peels ee RN FRONT MODE CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 83 Identifying Continuity Between Climate Control Unit
80. RIC CONVERSION CHART Display Reading Alphanumeric A thru A9 thru 9 30 thru 16 thru 9 BO thru B9 10 thru 19 14 thru 2 10 thru 19 CO thru C9 20 thru 29 4 thru 20 20 thru 29 DO thru D9 30 thru 39 22 thru 38 30 thru 39 EO thru E9 40 thru 49 40 thru 58 40 thru 49 FO thru F9 pT 100 thi 109 DTC TROUBLESHOOTING INDEX Checking the DTCs by HDS DTC TROUBLESHOOTING CHART 2008 Acura MDX 2007 09 HVAC Climate Control MDX Detection Item or DTC Symptom ECU DTC type B1200 Communication bus line Climate control unit Loss of communication error bus off Climate control unit Climate control unit Internal error internal error Climate control unit lost Climate control unit Loss of communication communication with gauge control module VSP NE message Climate control unit lost Climate control unit Loss of communication communication with gauge control module ECT message Climate control unit lost Climate control unit Loss of communication communication with gauge control module ILLUMI message An open in the rear Climate control unit Signal error evaporator temperature sensor circuit A short in the rear Climate control unit Signal error evaporator temperature sensor circuit An open or short in the X Climate control unit Signal error recirculation control motor circuit A problem in the rear Climate control unit Signal error blower motor circuit
81. Repair short to body ground in the wire NO Go to step 16 Turn the ignition switch to ON and check the same terminal for voltage to body ground CLIMATE CONTROL UNIT CONNECTOR A 40P ilelsts sijelo vf fre lia re fre 1 v 137 zt ssf sa ne ae an oom on se so se Wire side of female terminals Fig 75 Identifying Same Terminal For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR INC 15 there any voltage YES Repair short to power in the wire This short may have also damaged the climate control unit Repair the short to power before replacing the climate control unit NO Go to step 17 Turn the ignition switch to LOCK 0 Reconnect the climate control unit connector 40P Turn the ignition switch to ON II and measure the voltage between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P GRY IL Li DISHES ds Iv Ds D Tw s 7T o o 9 v e v s s Wire side of female terminals Fig 76 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX Is there about 5 V YES Go to step 20 NO Check for a loose wire or poor connection at climate control unit connector A 40P If the connection is good substitute a known go
82. S Go to step 6 NO Intermittent failure check for loose wire or poor connection on the climate control unit connector A 40P Check for DTCs with the HDS Are any of the following DTCs indicated B1958 B1063 or B1156 indicated YES Do the wiper washer switch combination switch control unit input test see WIPER WASHER SWITCH COMBINATION SWITCH CONTROL UNIT INPUT TEST NO Do the climate control unit troubleshooting see CLIMATE CONTROL UNIT TROUBLESHOOTING DTC B2970 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH RELAY CONTROL MODULE RM MESSAGE NOTE If you are troubleshooting multiple DTCs be sure to follow the instructions in dec res the B can system diagnosis test mode A see TROUBLESHOOTING B CAN SYSTEM DIAGNOSIS TEST MODE A Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Wait for 6 seconds or more Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS Check the DTCs Is DTC B2970 indicated YES Go to step 6 NO Intermittent failure check for loose wire or poor connection on the climate control unit connector A 40P Check for DTCs with the HDS 2008 Acura MDX 2007 09 HVAC Climate Control MDX Are any of the following DTCs indicated B1005 B1959 B2162 or B1158 indicated YES Do the relay control module input test see GAUGE CONTROL MODULE INPUT TEST NO Do the climate control unit t
83. STIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1229 or E and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the sunlight sensor circuit Turn the ignition switch to LOCK 0 Disconnect the sunlight sensor 5P connector Disconnect climate control unit connector A 40P Check for continuity between climate control unit connector A 40P No 29 terminal and the sunlight sensor 5P connector No 4 terminal 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals FTETSTSTSTS Te sTeToTe TeTeTe Tow 9 77 LL oe m zr e v v 7177 qj p PUR SUNLIGHT SENSOR 5P CONNECTOR Wire side of female terminals Fig 52 Identifying Continuity Between No 29 And Sunlight Sensor 5P Connector No 4 Terminal Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 9 NO Repair open in the wire between the climate control unit and the sunlight sensor 9 Check for continuity between climate control unit connector A 40P No 8 terminal and the sunlight sensor 5P connector No 2 terminal CLIMATE CONTROL UNIT CONNECTOR 40P Wire side of female terminals RED Te o T Tu o Te T IZ Te farT oT aT m Tn oe wo uo T7 SUNLIGHT SENSOR 5P CONNECTOR Wire side of female terminals Fig 53 Identifying Conti
84. TION WITHOUT THE HDS Check for DTCs Is DTC B1223 or M indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the rear blower motor circuit Tur the ignition switch to LOCK 0 Check the No 2 RR BLOWER 30 A fuse in the under hood fuse box and the No 30 10 A fuse in the under dash fuse relay box Are the fuses OK YES Go to step 7 NO Replace the fuse s and recheck If fuse s blow again check for a short in the No 2 RR BLOWER 30 A and No 30 10 A fuse s circuit Connect the rear blower motor 2P connector No 2 terminal to body ground with a jumper wire REAR BLOWER MOTOR 2P CONNECTOR ORN JUMPER WIRE Wire side of female terminals Fig 34 Identifying Rear Blower Motor 2P Connector No 2 Terminal To Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Turn the ignition switch to ON Does the rear blower motor run at high speed YES Go to step 9 NO Go to step 24 Turn the ionition ewitch to T 2008 Acura MDX 2007 09 HVAC Climate Control MDX 10 Disconnect the jumper wire 11 Disconnect the rear power transistor 4P connector 12 Check for continuity between the rear power transistor 4P connector No 2 terminal and body ground REAR POWER TRANSISTOR 4P CONNECTOR 5 Wire side of female terminals Fig 35 Identifying Continuity Between Rear Power Transistor 4P Connector No 2 Termina
85. VAC Climate Control MDX PCM CONNECTOR A 49P 2ps gt lt mm e e GB agas ooo RED JUMPER WIRE Terminal side of female terminals Fig 158 Identifying PCM Connector A 49P No 13 Terminal To Body Ground Courtesy of AMERICAN HONDA MOTOR INC 18 Turn the ignition switch to ON II Does the A C compressor click YES Check for loose wires or poor connections at PCM connector A 49P If the connections are good check the PCM grounds If the grounds are good substitute a known good PCM and recheck If the symptom indication goes away replace the original PCM see PCM REPLACEMENT NO Repair open in the wire between the A C compressor clutch relay and the PCM 19 Disconnect the jumper wire 20 Disconnect the A C compressor clutch 1P connector 2 Check for continuity between the A C compressor clutch relay 4P socket No 2 terminal and the A C compressor clutch 1P connector No 1 terminal A C COMPRESSOR CLUTCH RELAY 4P SOCKET RED A C COMPRESSOR CLUTCH 1P CONNECTOR Wire side of female termina Fig 159 Identifying Continuity Between A C Compressor Clutch Relay 4P Socket No 2 And No 1 2008 Acura MDX 2007 09 HVAC Climate Control MDX Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check the A C compressor clutch clearance and the compressor clutch field coil see A C COMPRESSOR CLUTCH CHECK Repair as needed NO
86. YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the front blower motor circuit 5 Turn the ignition switch to LOCK 0 6 Check the No 12 40 A fuse in the relay block and the No 30 10 A fuse in the under dash fuse relay box Are the fuses OK YES Go to step 7 NO Renlace the fisels and recheck Tf firce e hlaw again check for a hort in the No 19 A0 A and 2008 Acura MDX 2007 09 HVAC Climate Control MDX 7 10 11 12 No 30 10 A fuse s circuit Connect the front blower motor 2P connector No 2 terminal to body ground with a jumper wire FRONT BLOWER MOTOR 2P CONNECTOR GRN JUMPER WIRE Wire side of female terminals Fig 85 Identifying Front Blower Motor 2P Connector No 2 Terminal To Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Turn the ignition switch to ON Does the front blower motor run at high speed YES Go to step 9 NO Go to step 24 Turn the ignition switch to LOCK 0 Disconnect the jumper wire Disconnect the front power transistor 4P connector Check for continuity between the front power transistor 4P connector No 2 terminal and body ground FRONT POWER TRANSISTOR 4P CONNECTOR 1 BLK 3 Wire side of female terminals hin Fig 86 Identifying Continuity Between Front Power Transistor 4P Connector No 2 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continu
87. ate Control MDX NO Replace the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR REPLACEMENT 7 Disconnect the driver s air mix control motor 7P connector 8 Disconnect climate control unit connector A 40P 9 Check for continuity between the following terminals of climate control unit connector A 40P and the driver s air mix control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals nnnn DRIVER S AIR MIX CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 60 Identifying Continuity Between Climate Control Unit A 40P And Driver s Air Mix Control Motor 7P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Check for loose wires or poor connections at climate control unit connector A 40P and at the driver s air mix control motor 7P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Repair open in the wire s between the climate control unit and the driver s air mix control motor DTC B1234 OR DTC INDICATOR K AND AUTO A SHORT IN THE DRIVER S AIR MIX CONTROL MOTOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 10 2008 Acu
88. ate control unit and recheck If the symptom indication goes away replace the original climate control unit 20 While checking the same terminal for voltage to ground reconnect these items individually and note the voltage reading each time e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor A C pressure sensor CLIMATE CONTROL UNIT CONNECTOR A 40P r te Wire side of female terminals Fig 117 Identifying Climate Control Unit Connector A 40P Courtesy of AMERICAN HONDA MOTOR CO INC Does the voltage remain at about 5 V YES Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the component that caused the voltage drop DTC B2969 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH COMBINATION SWITCH CONTROL UNIT WIPSW MESSAGE NOTE If you are troubleshooting multiple DTCs be sure to follow the instructions in the B can system diagnosis test mode A see TROUBLESHOOTING B CAN SYSTEM DIAGNOSIS TEST MODE A 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK and then ON ID 2008 Acura MDX 2007 09 HVAC Climate Control MDX Wait for 6 seconds or more Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS Check the DTCs Is DTC B2969 indicated YE
89. ator and the evaporator becomes very cold and absorbs the heat from the ambient air The blower fan pushes air across the evaporator where the heat is absorbed and then it blows the cool air into the passenger compartment 2008 Acura MDX 2007 09 HVAC Climate Control MDX EXPANSION VALVE Meters the required amount of into the evaporator _ FRONT BLOWER FAN FRONT EVAPORATOR Absorption of heat FRONT EVAPORATOR TEMPERATURE SENSOR P a a pem RELIEF VALVE A C PRESSURE SENSOR Relieves pressure at the A C junge Triple function when the pressure is too high When the refrigerant i is below 196 kPa 2 0 kgf cm 28 psi or above 3 140 kPa 32 k 455 psi the PCM turns t compressor relay to tL PER e A C compressor 7 A C COMPRESSOR Suction and compression GE HIGH PRESSURE VAPOR HIGH PRESSURE LIQUID CONDENSER Radiation eat RECEIVER DRYER LOW PRESSURE LIQUID DESICCANT Traps debris and debris and E LOW PRESSURE VAPOR Fig 12 Climate Control System Description Courtesy of AMERICAN HONDA MOTOR CO INC This vehicle uses HFC 134a R 134a refrigerant which does not contain chlorofluorocarbons Pay attention to the following service items e Do not mix refrigerants CFC 12 R 12 and HFC 134a R 134a They are not compatible e Use only the recommended polyalkyleneglycol PAG refrigerant oil DENSO ND OIL 8 de
90. box see GLOVE BOX REMOVAL INSTALLATION 2 Disconnect the 7P connector A from the passenger s air mix control motor B Remove the self tapping screws and the passenger s air mix control motor from the heater unit Fig 175 Identifying Passenger s Air Mix Control Motor And 7P Connector With Screws Courtesy of AMERICAN HONDA MOTOR INC 3 Install the motor in the reverse order of removal Make sure the pin on the motor is properly engaged with the linkage After installation make sure the motor runs smoothly FRONT MODE CONTROL MOTOR TEST 2008 Acura MDX 2007 09 HVAC Climate Control MDX NOTE Before testing check for HVAC DTCs see GENERAL TROUBLESHOOTING INFORMATION 1 Disconnect the 7P connector from the front mode control motor NOTE Incorrectly applying power and ground to the front mode control motor will damage it Follow the instructions carefully 2 Connect battery power to the No 1 terminal of the front mode control motor and ground the No 2 terminal the front mode control motor should run smoothly and stop at Vent If it doesn t reverse the connections the front mode control motor should run smoothly and stop at Defrost When the front mode control motor stops running disconnect battery power immediately FRONT MODE CONTROL MOTOR Fig 176 Identifying Front Mode Control Motor Connector Terminals Courtesy of AMERICAN HONDA MOTOR CO INC
91. cing the climate control unit NO Go to step 17 17 Turn the ignition switch to LOCK 0 18 Reconnect the climate control unit connector 40P 19 Turn the ignition switch to ON and measure the voltage between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 66 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there about 5 V YES Go to step 20 NO Check for a loose wire or poor connection at climate control unit connector A 40P If the connection is good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit 20 2008 Acura MDX 2007 09 HVAC Climate Control MDX While checking the same terminal for voltage to ground reconnect these items individually and note the voltage reading each time e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor CLIMATE CONTROL UNIT CONNECTOR A 40P 11213 141818 L7 1o alalu n 71 Wire side of female terminals Fig 67 Identifying Climate Control Unit Connector A 40P Courtesy of AMERICAN HONDA MOTOR CO INC Does th
92. climate control unit has a mode that displays sensor inputs it receives This mode shows you what the climate control unit is receiving from each of the sensors one at a time and it can help you determine if a sensor is faulty CHECK THESE ITEMS BEFORE USING THE SENSOR INPUT DISPLAY MODE 1 Turn the ignition switch to ON and check the recirculation door function press the recirculation button to switch from FRESH to RECIRC The air volume and sound should change slightly 2 Set the temperature control knob to the desired test temperature When selecting the test temperature note these items e Lo temperature setting will default to MAX COOL VENT and RECIRC e Hi temperature setting will default to MAX HOT FLOOR and FRESH e 58 through 86 F settings will use the automatic climate control logic 3 Turn the ignition switch to LOCK 0 TO RUN THE SENSOR INPUT DISPLAY MODE FOLLOW THESE STEPS 2008 Acura MDX 2007 09 HVAC Climate Control MDX 1 Turn the ignition switch to LOCK 0 2 Press and hold both the AUTO and RECIRCULATION CONTROL buttons then start the engine 3 After the engine starts release both buttons The display panel control unit will flash the sensor number and then the value for that sensor Record the value displayed 4 To advance to the next sensor press the REAR WINDOW DEFOGGER button SENSOR DISPLAYED CHART Displayed Value 1 Temperature 2 Outside Air Temperatur
93. dy ground and climate control unit connector A 40P No 14 and No 15 terminals individually CLIMATE CONTROL UNIT CONNECTOR A 40P LTGRN YEL ee e De o o Da e o To T Tw Lana To o en o o e T7 HO IHO Wire side of female terminals Fig 79 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 40P No 14 And No 15 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the passenger s air mix control motor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1239 OR DTC INDICATOR A AN OPEN OR SHORT IN THE FRONT MODE CONTROL MOTOR CIRCUIT 1 2 3 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1239 or A indicated 2008 Acura MDX 2007 09 HVAC Climate Control MDX YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the front mode control motor circuit Turn the ignition switch to LOCK 0 Test the front mode control motor
94. e Check for DTCs Are these DTCs also present B1234 or and AUTO and or B1237 or and AUTO and or B1245 or and or B2968 or A and WINDSHIELD DEFROST YES Go to step 16 NO Go to step 6 Turn the ignition switch to LOCK 0 Disconnect the A C pressure sensor 3P connector Disconnect climate control unit connector A 40P Check for continuity between body ground and climate control unit connector A 40P No 26 terminal CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 120 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 2008 Acura MDX 2007 09 HVAC Climate Control MDX 10 11 40P No 26 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the A C pressure sensor NO Go to step 10 Check for continuity between climate control unit connector A 40P No 6 and No 26 terminals CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals Fig 121 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 And No 26 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair the short in the wires NO Go to step 11 Turn the ignition switch to ON ID and measure the voltage between body ground and climate control unit connector A 40P No 26 terminal
95. e Solar Radiation Sensor Value Dark 00 Flashlight 04 Cloudy 10 Sunny 65 4 Front Evaporator Outlet Air Temperature Passenger s Air Mix Opening Low value indicates cooler air distribution higher value indicates warmer air distribution Cot openng Vent Temperature Air Out TAO C Vehicle Speed Vehicle must be driven to display speed km h A C Pressure 10 kPa Rear Vent Temperature Air Out TAO 6 7 9 Rear Air Mix Opening of opening A B Rear Evaporator Outlet Air Temperature C C D FogMargin 0 0 0 0 0 0 C NOTE e The sensor values will be displayed in degrees Celsius C or an alphanumeric code Use the chart to convert the value to degrees Fahrenheit F e If the sensor value displays Er this indicates there is an open or short in the circuit or sensor Check for DTCs using the HDS or refer to CHECKING DTCS by DTC indication e If necessary compare the sensor input display to a known good vehicle under the same test conditions e If the sensor is out of the normal range refer to the sensor test or substitute a known good sensor and recheck 5 To cancel the sensor input display mode press the AUTO button or turn the ignition switch to LOCK 0 Celsius to Fahrenheit Conversion Table 2008 Acura MDX 2007 09 HVAC Climate Control MDX CELSIUS TO FAHRENHEIT CONVERSION CHART Alphanumeric Conversion Table ALPHANUME
96. e readings will not change under the light of a flashlight or a fluorescent lamp Voltage should be 3 6 3 7 V or more with the sensor out of direct sunlight e 3 3 3 5 V or less with the sensor in direct sunlight 2008 Acura MDX 2007 09 HVAC Climate Control MDX Probe On No 2 Terminal With Connector Courtesy of AMERICAN HONDA MOTOR CO INC 4 Ifthe voltage is not as specified replace the sunlight sensor see SUNLIGHT SENSOR REPLACEMENT SUNLIGHT SENSOR REPLACEMENT 1 Remove the sunlight sensor A from the dashboard then disconnect the 5P connector B Be careful not to damage the sensor and the dashboard Fig 166 Identifying Sunlight Sensor And 5P Connector Courtesy of AMERICAN HONDA MOTOR CO INC 2 Install the sensor in the reverse order of removal FRONT EVAPORATOR TEMPERATURE SENSOR TEST 1 Remove the evaporator front temperature sensor see FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT 2 Dip the sensor in ice water and measure the resistance between its terminals 5 2008 2007 09 HVAC Climate Control FRONT EVAPORATOR TEMPERATURE SENSOR bead Terminal side of male terminals Fig 167 Measuring Resistance Between Evaporator Front Temperature Sensor Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Then pour warm water on the sensor and check for a change in the resistance Compare the resistance readings with the speci
97. e to the front evaporator 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft Front suction line to the front evaporator 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft D Front suction line to the suction hose 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 Ibf ft Suction hose to the A C compressor 6 x 1 0 mm 9 8 N m 1 0 kgf m 7 2 9 A C compressor to the A C compressor bracket 8 x 1 25 mm 22 2 2 kgf m 16 2 Ibf ft 10 A C compressor to the engine block 10 x 1 25 mm 45 N m 4 6 kgf m 33 2 Ibf ft Fig 5 Identifying Front A C Line Courtesy of AMERICAN HONDA MOTOR INC A C SYSTEM INSPECTION Before troubleshooting any problem with the air conditioning system do the following 2008 Acura MDX 2007 09 HVAC Climate Control MDX 1 With the ignition switch in the LOCK 0 inspect the A C components pressure lines and hoses for stains that may indicate a refrigerant or a compressor oil leak Fig 6 Identifying Compressor Oil Leak Courtesy of AMERICAN HONDA MOTOR CO INC 2 Check the condenser for material clogging the fins or for damage to the fins e Carefully clean any material from the condenser fins with water and detergent e Be sure to dry the condenser completely CONDENSER 7 Identifying Condenser Courtesy of AMERICAN HONDA MOTOR CO INC 3 Inspect the drive belt see DRIVE BELT INSPECTION 4 Make sure no material is blocking the airflow to the condenser 5 C
98. e voltage remain at about 5 V YES Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the component that caused the voltage drop DTC B1235 OR DTC INDICATOR L AND AUTO A PROBLEM IN THE DRIVER S AIR MIX CONTROL LINKAGE DOOR OR MOTOR CIRCUIT 1 2 3 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1235 or L and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the driver s air mix control motor circuit 10 2008 Acura MDX 2007 09 HVAC Climate Control MDX Turn the ignition switch to LOCK 0 Test the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR TEST Is the driver s air mix control motor OK YES Go to step 7 NO Replace the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR REPLACEMENT or repair the driver s air mix control linkage or door Disconnect the driver s air mix control motor 7P connector Disconnect climate control unit connector A 40P Check for continuity between the following terminals of climate control unit connector A 40P and the driver s air
99. emove the center bolt while holding the pressure plate A with a commercially available A C clutch holder B 7 18 N m T 1 8 kgf m 13 Ibf ft Fig 213 Identifying Center Bolt While Holding Pressure Plate With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 2 Remove the pressure plate A and shim s B taking care not to lose the shim s If the clutch needs adjustment increase or decrease the number and thickness of shims as necessary then reinstall the pressure plate and recheck its clearance see A C COMPRESSOR CLUTCH CHECK NOTE The shims are available in three thicknesses 0 1 mm 0 3 mm and 0 5 mm 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 214 Identifying Pressure Plate And Shim Courtesy of AMERICAN HONDA MOTOR INC 3 If you are replacing the field coil remove the snap ring A with snap ring pliers then remove the pulley B Be careful not to damage the pulley or the A C compressor Fig 215 Identifying Snap Ring And Pulley Courtesy of AMERICAN HONDA MOTOR INC 4 Remove the screw from the field coil ground terminal A and bracket B Disconnect the connector C from the field coil then remove the wire harness clip D Remove the snap ring E with snap ring pliers then remove the field coil F Be careful not to damage the field coil or the A C compressor 5 2008 2007 09 HVAC Climate Control Fi
100. en the No 4 and No 3 terminals of the humidity in car temperature sensor with the specifications shown in the graph the resistance should be within the specifications HUMIDITY IN CAR TEMPERATURE SENSOR 12 10 E t 9 LLL i ZEN 82 J 8 RESISTANCE 7 1 1 14 32 50 68 86 104 F 10 0 10 20 30 40T TEMPERATURE Fig 161 Resistance To Temperature Graph Courtesy of AMERICAN HONDA MOTOR INC 5 Ifthe resistance is not as specified replace the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT 1 Remove the driver s dashboard lower cover see DRIVER S DASHBOARD LOWER COVER REMOVALU INSTALLATION 2008 Acura MDX 2007 09 HVAC Climate Control MDX 2 Remove the humidity in car temperature sensor A from the driver s dashboard lower cover B Fig 162 Identifying Humidity In Car Temperature Sensor And Driver s Dashboard Lower Cover Courtesy of AMERICAN HONDA MOTOR CO INC 3 Install the sensor in the reverse order of removal Be sure to connect the air hose securely OUTSIDE AIR TEMPERATURE SENSOR TEST 1 Remove the outside air temperature sensor see OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT 2 Dip the sensor in ice water and measure the resistance Then pour warm water on the sensor and check for a change in resistance 3 Compare the res
101. ensor Circuit E and AUTO F and AUTO 2008 Acura MDX 2007 09 HVAC Climate Control MDX G and AUTO Hand AUTO Jand AUTO K and AUTO L and AUTO An open in the front evaporator temperature sensor circuit see DTC B1231 or DTC indicator G and AUTO An Open in the Front Evaporator Temperature Sensor Circuit A short in the front evaporator temperature sensor circuit see DTC B1232 or DTC indicator H and AUTO A Short in the Front Evaporator Temperature Sensor Circuit An open in the driver s air mix control motor circuit see DTC B1233 or DTC indicator J and AUTO An Open in the Driver s Air Mix Control Motor Circuit A short in the driver s air mix control motor circuit see DTC B1234 or DTC indicator K and AUTO A Short in the Driver s Air Mix Control Motor Circuit A problem in the driver s air mix control linkage door or motor circuit see DTC B1235 or DTC indicator L and AUTO A Problem in the Driver s Air Mix Control Linkage Door or Motor Circuit M and AUTO N and AUTO An open in the passenger s air mix control motor circuit see DTC B1236 or DTC indicator M and AUTO An Open in the Passenger s Air Mix Control Motor Circuit A short in the passenger s air mix control motor circuit see DTC B1237 or DTC indicator N and AUTO A Short in the Passenger s Air Mix Control Motor Circuit P and AUTO A problem in the passenger s air mix control linkage door or motor circuit
102. ent air intake temperature chart e Mark the high side discharge pressure pressure on the vertical line e Mark the ambient air intake temperature on the bottom line e Draw a vertical line from the ambient air intake temperature mark e Draw a horizontal line from the high side discharge pressure mark until it intersects the vertical line 2008 Acura MDX 2007 09 HVAC Climate Control MDX NOTE The high side pressure and ambient air temperature should intersect in the shaded area Any measurements outside the area may indicate the need for further inspection Ambient Intake Temperature vs High Side Discharge Pressure kPa kgf cm ipa 1 600 16 3 232 Je 1 400 142 232 1 200 12 2 174 HIGH SIDE DISCHARGE PRESSURE 000 10 140 ALL es ee a en 800 8 2 116 68 77 95 104 F 20 25 30 35 40 AMBIENT INTAKE TEMPERATURE Fig 230 Ambient Intake Temperature Vs High Side Discharge Pressure Graph Courtesy of AMERICAN HONDA MOTOR INC 10 To complete the low side suction pressure ambient air intake temperature chart e Mark the low side suction pressure along the vertical line e Mark the ambient air intake temperature along the bottom line 2008 Acura MDX 2007 09 HVAC Climate Control MDX e Draw a vertical line from the ambient air intake temperature mark e Draw a horizontal line from the low side sucti
103. erable run the engine at idle speed and let the air conditioning work for a few minutes then shut the engine off n Recover the refrigerant with a recovery recycling charging station see REFRIGERANT RECOVERY Remove the drive belt see DRIVE BELT INSPECTION Remove the front splash shield see SPLASH SHIELD REPLACEMENT Remove the front undercover see FRONT UNDERCOVER REPLACEMENT Support the front subframe with the engine support Remove the bolts and the front subframe stiffener A ON oi 309 NOTE Install the new front subframe mounting bolt B 2008 Acura MDX 2007 09 HVAC Climate Control MDX 14 x 1 5 mm 103 0 10 5 kgf m 75 9 Ibf ft Replace Fig 207 Identifvine Front Subframe Stiffener And Mounting Bolts With Torque Specifications Courtesy of AMERICAN HONDA MOTOR INC Disconnect the A C compressor clutch connector A Remove the bolts and the nut then disconnect the suction hose B and discharge hose C from the A C compressor Plug or cap the lines immediately after disconnecting them to avoid moisture and dust contamination Fig 208 Identifying A C Compressor Clutch Connector Suction Hose And Discharge Hose With Torque Specification Courtesy of AMERICAN HONDA MOTOR INC Remove the mounting bolts and the A C compressor A Be careful not to damage the radiator fins when removing the compressor 2008 Acura MDX 2007 09 HVAC Climate Control
104. es away replace the original climate control unit NO Replace the sunlight sensor see SUNLIGHT SENSOR REPLACEMENT DTC B1231 OR DTC INDICATOR G AND AUTO AN OPEN IN THE FRONT EVAPORATOR TEMPERATURE SENSOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION 2008 Acura MDX 2007 09 HVAC Climate Control MDX WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1231 or and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the front evaporator temperature sensor circuit Turn the ignition switch to LOCK 0 Remove the front evaporator temperature sensor see FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT and test it see FRONT EVAPORATOR TEMPERATURE SENSOR TEST 15 the front evaporator temperature sensor OK YES Go to step 7 NO Replace the front evaporator temperature sensor Disconnect climate control unit connector A 40P Check for continuity between climate control unit connector A 40P No 24 terminal and the front evaporator temperature sensor 2P connector No 2 terminal CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals pug FRONT EVAPORATOR TEMPERATURE
105. fications shown in the graph the resistance should be within the specifications 30 RESISTANCE 20 TEMPERATURE Fig 168 Resistance To Temperature Graph Courtesy of AMERICAN HONDA MOTOR INC If the resistance is not as specified replace the front evaporator temperature sensor see FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT FRONT EVAPORATOR TEMPERATURE SENSOR REPLACEMENT 1 Remove the driver s dashboard undercover see DRIVER S DASHBOARD UNDERCOVER REMOVAL AINSTALLATION Remove the TPMS control unit see TPMS CONTROL UNIT REPLACEMENT Disconnect the connector A from the front evaporator temperature sensor B then remove the connector clip C Remove the self tapping screw and the front evaporator temperature sensor 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 169 Identifying Front Evaporator Temperature Sensor Connector And Connector Cli Courtesy of AMERICAN HONDA MOTOR CO INC 4 Install the sensor in the reverse order of removal FRONT POWER TRANSISTOR TEST 1 Remove the passenger s dashboard undercover see PASSENGER S DASHBOARD UNDERCOVER REMOVAL INSTALLATION 2 Disconnect the 4P connector from the front power transistor 3 Measure the resistance between the No 3 and No 4 terminals of the front power transistor It should be about 1 5 kohms e If the resistance is within the specifications go to step 4 e If the resistance is
106. g 216 Identifying Field Coil Ground Terminal Bracket Connector Wire Harness Clip And Snap Ring Courtesy of AMERICAN HONDA MOTOR CO INC Reassemble the clutch in the reverse order of disassembly and note these items e Install the field coil with the wire side facing down and align the boss on the field coil with the hole in the A C compressor e Clean the pulley and A C compressor sliding surfaces with contact cleaner or other non petroleum solvent e Install new snap rings note the installation direction and make sure they are fully seated in the groove e Make sure that the pulley turns smoothly after it s reassembled e Route and clamp the wires properly or they can be damaged by the pulley A C COMPRESSOR RELIEF VALVE REPLACEMENT 1 Recover the refrigerant with a recovery recycling charging station see REFRIGERANT RECOVERY Remove the front splash shield see SPLASH SHIELD REPLACEMENT Remove the front undercover see FRONT UNDERCOVER REPLACEMENT Remove the relief valve A and the O ring B Plug the opening to keep foreign matter from entering the system and the A C compressor oil from running out 2008 Acura MDX 2007 09 HVAC Climate Control MDX 13 2 N m 1 35 kgf m 9 7 Ibf ft Fig 217 Identifying Relief Valve And O Ring With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 5 Clean the mating surfaces 6 Replace the O ring with a new one at the relief valve and
107. g check for powertrain DTCs see GENERAL TROUBLESHOOTING INFORMATION Check the No 17 7 5 A fuse in the relay block and the No 30 10 A fuse in the under dash fuse relay box Are the fuses OK YES Go to step 2 NO Replace the fuse s and recheck If the fuse s blow again check for a short in the No 17 7 5 A and No 30 10 A fuse s circuit Connect the HDS to the DLC Start the engine Turn on the A C Check the A C CLUTCH in the PGM FI Data List with the HDS Is the A C CLUTCH on YES Go to step 7 NO Go to step 6 Using the HDS confirm the following values in the PGM FI Data List at idle A C SWITCH REFERENCE CHART AIC SWITCH A C PRESSURE SENSOR 196 3 138 kPa 2 32 kgf cm 28 455 psi 2008 Acura MDX 2007 09 HVAC Climate Control MDX Are all the values within specifications YES Go to step 7 NO Troubleshoot the value that is not within the specifications 7 Remove the A C compressor clutch relay from the relay block and test it see POWER RELAY TEST Is the relay OK YES Go to step 8 NO Replace the A C compressor clutch relay 8 Measure the voltage between the A C compressor clutch relay 4P socket No 1 terminal and body ground A C COMPRESSOR CLUTCH RELAY 4P SOCKET Fig 155 Measuring Voltage Between A C Compressor Clutch Relay 4P Socket No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there battery voltage YES Go
108. h to Recirculate e Turn the A C switch ON and the fan switch to Max e Run the engine at 1 500 rpm e No driver or passengers in vehicle 7 After running the air conditioning for 10 minutes under the above test conditions read the delivery temperature from the thermometer in the center vent the intake temperature near the blower unit and the discharge high and suction low pressures on the A C gauges 8 To complete the vent delivery ambient air intake temperature chart e Mark the vent delivery temperature on the vertical line e Mark the ambient air intake temperature on the bottom line e Draw a vertical line from the ambient air intake temperature mark e Draw a horizontal line from the vent delivery temperature mark until it intersects the vertical line NOTE The vent temperature and ambient air temperature should intersect in the shaded area Any measurements outside the area may indicate the need for further inspection 2008 Acura MDX 2007 09 HVAC Climate Control MDX Ambient Intake Temperature vs Vent Delivery Temperature c 86 4 30 HUMIDITY LEVEL 80 30 VENT DELIVERY 59 TEMPERATURE 15 0 a 68 77 86 95 104 T 20 25 30 35 140 9 AMBIENT INTAKE TEMPERATURE Fig 229 Ambient Intake Temperature Vs Vent Delivery Temperature Graph Courtesy of AMERICAN HONDA MOTOR CO INC 9 To complete the high side discharge pressure ambi
109. he self tapping screws and the passenger s heater duct A Remove the self tapping screws and the expansion valve cover B Remove the self tapping screw and the front heater core cover C Remove the self tapping screws the heater pipe brackets D the grommets E and carefully pull out the front heater core F Fig 203 Identifying Passenger s Heater Duct Expansion Valve Cover Front Heater Core Cover And Grommets Courtesy of AMERICAN HONDA MOTOR INC Install the front heater core and the front evaporator core in the reverse order of removal TInctall the heater unit in the reverse order of removal and note these items 2008 Acura MDX 2007 09 HVAC Climate Control MDX e Do not interchange the inlet and outlet heater hoses and install the hose clamps securely e Refill the cooling system with engine coolant see COOLANT CHECK e Adjust the heater valve cable see HEATER VALVE CABLE ADJUSTMENT e Make sure that there is no coolant leakage e Make sure that there is no air leakage e Refer to the FRONT EVAPORATOR CORE REPLACEMENT 17 Do the battery terminal reconnection procedure see BATTERY TERMINAL DISCONNECTION AND RECONNECTION HEATER VALVE CABLE ADJUSTMENT 1 From under the hood open the cable clamp A then disconnect the heater valve cable B from the heater valve arm C Fig 204 Identifying Cable Clamp Heater Valve Cable And Heater Valve Arm Courtesy of AMERICAN HONDA MOTOR CO
110. heck the dust and pollen filter and replace it if it is clogged see DUST AND POLLEN FILTER REPLACEMENT 6 Check the operation of the heater valve Make sure the cable is adjusted properly see HEATER VALVE CABLE ADJUSTMENT 7 Start the engine turn the air conditioning system on and allow it to normalize for a few minutes 8 Check that the A C operates at each position of the blower fan switch except OFF 9 Check that the compressor clutch is engaged The pressure plate should be rotating at the same speed as the pulley 2008 Acura MDX 2007 09 HVAC Climate Control MDX 10 Check that the cooling fans operate when the compressor clutch is engaged 11 Check that the engine idle speed is correctly maintained when the A C is switched on and off when the compressor clutch is engaged and disengaged RADIATOR J A C CONDENSER FAN A C COMPRESSOR Fig 8 Identifying Radiator Fan A C Condenser Fan And A C Compressor Courtesy of AMERICAN HONDA MOTOR INC GENERAL TROUBLESHOOTING INFORMATION HOW TO CHECK FOR DTCS WITH THE HDS 1 Make sure the ignition switch is LOCK 0 2 Connect the HDS to the data link connector DLC A located under the driver s side of the dashboard 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 9 Connecting HDS To DLC Courtesy of AMERICAN HONDA MOTOR INC Turn the ignition switch to ON II Make sure the HDS communicates with the vehicle a
111. here continuity 19 20 21 2008 2007 09 HVAC Climate Control YES Repair short to body ground in the wire s between the climate control unit and the front power transistor NO Go to step 19 Check for continuity between the following terminals of climate control unit connector A 40P and the front power transistor 4P connector 40 No 9 No 3 No 10 No 1 CLIMATE CONTROL UNIT CONNECTOR A 40 Wire side of female terminals BLU RED FRONT POWER TRANSISTOR 4P CONNECTOR Wire side of female terminals Fig 89 Identifying Continuity Between Climate Control Unit A 40P And Front Power Transistor 4P Connector Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 20 NO Repair open in the wire s between the climate control unit and the front power transistor Turn the ignition switch to ON II Measure the voltage between body ground and climate control unit connector A 40P No 9 and No 10 terminals individually 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals Fig 90 Measuring Voltage Between Body Ground And Climate Control Unit Connector A 40P No 9 And No 10 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there any voltage YES Repair short to power in the wire s NO
112. ing charging station see REFRIGERANT RECOVERY 2 Remove the bolts 6 x 1 0 9 mm 8 1 0 kgf m 7 2 Ibf ft Fig 190 Identifvine Front Evaporator Core Bolts With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 3 Remove the bolts then disconnect the front receiver line A and the front suction line B from the front evaporator core 2008 Acura MDX 2007 09 HVAC Climate Control MDX 9 8N m 1 0 kgf m 7 2 Ibf ft Fig 191 Identifying Front Receiver Line And Front Suction Line Bolts With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 4 Remove the blower unit see BLOWER UNIT REMOVAL INSTALLATION 5 Disconnect the connector A from the front power transistor then remove the harness clip B Remove the self tapping screws the expansion valve cover C and the seal D Fig 192 Identifying Front Power Transistor Connector Harness Clip Expansion Valve Cover And Seal Courtesy of AMERICAN HONDA MOTOR CO INC 6 Remove the bolts the inlet and outlet pipes A and expansion valve B Carefully pull out the front 2008 Acura MDX 2007 09 HVAC Climate Control MDX evaporator core C then remove the plate D Fig 193 Identifying Inlet And Outlet Pipes Expansion Valve Front Evaporator Core And Plate Courtesy of AMERICAN HONDA MOTOR INC 7 Install the core in the reverse order of removal and note these items
113. ircuit An open or short in the recirculation control motor circuit see DTC B1215 or DTC indicator J An Open or Short in the Recirculation Control Motor Circuit A problem in the recirculation control linkage door or motor circuit see DTC B2983 or DTC indicator K A problem in the Recirculation Control Linkage Door or Motor Circuit A problem in the rear blower motor circuit see DTC B1223 or DTC indicator M A Problem in the Rear Blower Motor Circuit An open in the rear evaporator temperature sensor circuit see DTC B1213 or DTC indicator N An Open in the Rear Evaporator Temperature Sensor Circuit A short in the rear evaporator temperature sensor circuit see DTC B1214 or DTC indicator P A Short in the Rear Evaporator Temperature Sensor Circuit An open in the humidity sensor circuit see B2967 or DTC indicator A and WINDSHIELD DEFROST An Open in the Humidity Sensor 2 Circuit a short in the humidity sensor circuit see DTC 2968 or DTC indicator A and WINDSHIELD DEFROST A Short in the Humidity Sensor Circuit An open in the A C pressure sensor circuit see DTC B2979 or DTC Band WINDSHIELD indicator B and WINDSHIELD DEFROST An Open in the A C DEFROST Pressure Sensor Circuit a short in A C pressure sensor circuit see DTC B2980 or DTC indicator B and WINDSHIELD DEFROST A short in the A C Pressure Sensor Circuit DISPLAYING SENSOR INPUTS AT THE CLIMATE CONTROL UNIT The
114. istance reading between the No 1 and No 2 terminals of the outside air temperature sensor with the specifications shown in the graph the resistance should be within the specifications OUTSIDE AIR TEMPERATURE SENSOR RESISTANCE 14 32 50 68 86 104 10 0 10 20 30 40 TEMPERATURE 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 163 Resistance To Temperature Graph Courtesy of AMERICAN HONDA MOTOR INC 4 Ifthe resistance is not as specified replace the outside air temperature sensor see OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT 1 Remove the bulkhead cover see FRONT BULKHEAD COVER REPLACEMENT 2 Lift the tab A to release the lock then remove the outside air temperature sensor B from the back of the front bumper Disconnect the 2P connector C from the outside air temperature sensor Fig 164 Identifying Tab Air Temperature Sensor And 2P Connector Courtesy of AMERICAN HONDA MOTOR CO INC 3 Install the sensor in the reverse order of removal SUNLIGHT SENSOR TEST 1 Remove the sunlight sensor from the dashboard see SUNLIGHT SENSOR REPLACEMENT 2 Connect the sunlight sensor 5P connector 3 Turn the ignition switch to ON II Measure the voltage between the terminals with the probe on the No 4 terminal and the probe on the No 2 terminal with the connector connected NOTE The voltag
115. it An open or short in the X Climate control unit Signal error front mode control motor circuit A problem in the front Climate control unit Signal error mode control linkage doors or motor circuit A problem in the front Climate control unit Signal error blower motor circuit An open in the rear air Climate control unit Signal error mix control motor circuit A short in the rear air mix Climate control unit Signal error control motor circuit 246 A problem in the rear air Climate control unit Signal error mix control linkage door or motor circuit Climate control unit lost Climate control unit Loss of communication communication with rear climate control panel B2967 An open in the humidity Climate control unit Signal error sensor circuit A short in the humidity Climate control unit Signal error sensor circuit B2969 Climate control unit lost Climate control unit Loss of communication communication with combination switch control unit WIPSW B1236 B1237 B1238 B1239 B1240 B1241 B1244 B1245 B1 B2965 B2968 2008 Acura MDX 2007 09 HVAC Climate Control MDX Climate control unit lost Climate control unit Loss of communication communication with relay control module RM An open in the A C Climate control unit Signal error pressure sensor circuit A short in the A C Climate control unit Signal error pressure sensor circuit Climate control unit lost Climate control unit Loss of communication communicatio
116. ition switch to LOCK 0 Disconnect climate control unit connector B 14P Disconnect audio unit connector C 24P Check for continuity between climate control unit connector B 14P No 8 terminal and audio unit connector C 24P No 24 terminal CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of female terminals LL v i AUDIO UNIT CONNECTOR C 24P BLU Wire side of female terminals Fig 132 Identifying Continuity Between Climate Control Unit Connector B 14P No 8 And No 24 2008 Acura MDX 2007 09 HVAC Climate Control MDX Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 9 NO Repair open in the wire between the climate control unit and the audio unit 9 Check for continuity between climate control unit connector B 14P No 8 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of female terminals Fig 133 Identifying Continuity Between Climate Control Unit Connector B 14P No 8 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the audio unit NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit If the symptom indication remains substitute a known good audio unit If
117. ity YES Go to step 13 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Check for an open in the wire between the front power transistor and body ground If the wire is OK check for poor ground at G507 see GROUND TO COMPONENTS INDEX 13 Connect the front power transistor 4P connector No 2 and No 4 terminals with a jumper wire 14 15 16 17 18 FRONT POWER TRANSISTOR 4 CONNECTOR naes JUMPER WIRE 3 15 Wire side of female terminals Fig 87 Identifying Front Power Transistor 4P Connector No 2 And No 4 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Turn the ignition switch to ON II Does the front blower motor run at high speed YES Go to step 15 NO Repair open in the GRN wire between the front power transistor and the front blower motor Turn the ignition switch to LOCK 0 Disconnect the jumper wire Disconnect climate control unit connector A 40P Check for continuity between body ground and climate control unit connector A 40P No 9 and No 10 terminals individually CLIMATE CONTROL UNIT CONNECTOR A 40P ndi B aje nongo ee es n s m zr ms m e m IHO Wire side of female terminals Fig 88 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 40P No 9 And No 10 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is t
118. l And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Go to step 13 NO Check for an open in the wire between the rear power transistor and body ground If the wire is OK check for poor ground at G503 see GROUND TO COMPONENTS INDEX 13 Connect the rear power transistor 4P connector No 2 and No 4 terminals with a jumper wire REAR POWER TRANSISTOR 4P CONNECTOR T BU ET JUMPER WIRE 314 Wire side of fernale terminals Fig 36 Identifying Rear Power Transistor 4P Connector No 2 And No 4 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC 14 Turn the ignition switch to ON II Does the rear blower motor run at high speed YES Go to step 15 NO Repair open in the ORN wire between the rear power transistor and the rear blower motor 15 16 17 18 19 2008 2007 09 HVAC Climate Control Turn the ignition switch to LOCK 0 Disconnect the jumper wire Disconnect climate control unit connector B 14P Check for continuity between body ground and climate control unit connector B 14P No 13 and No 14 terminals individually CLIMATE CONTROL UNIT CONNECTOR 14 5 e EE RED BLU QQ r Wire side of female terminals Fig 37 Identifying Continuity Between Body Ground And Climate Control Unit Connector B 14P No 13 And No 14 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC
119. l motor see PASSENGER S AIR MIX CONTROL MOTOR REPLACEMENT Disconnect the passenger s air mix control motor 7P connector Disconnect climate control unit connector A 40P 10 Check for continuity between body ground and climate control unit connector A 40P No 30 terminal 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR 40 1 LETS TESTS Te d eT Te o Te Dee Tv Two LT ICIECEJEJXQEIEIEDBDEBEBDBEDDBEE BLU Vm Wire side of female terminals Fig 71 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 40P No 30 Terminal Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the passenger s air mix control motor NO Go to step 11 11 Check for continuity between climate control unit connector A 40P No 6 and No 30 terminals CLIMATE CONTROL UNIT CONNECTOR A 40P BHO 2 as 20 er 20 20 20 e 1 BLU Wire side of female terminals Fig 72 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 And No 30 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair the short in the wires NO Go to step 12 12 Turn the ignition switch to ON II and measure the voltage between climate control unit connector A 40P No 30 terminal and bod
120. limate control unit 13 Turn the ignition switch to LOCK 0 and disconnect the climate control unit 14 Disconnect these items e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor 15 Check for continuity between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40 T Bs amena Te oT o m m n v v v 7 Wire side of female terminals Fig 64 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there continuity YES Repair short to body ground in the wire NO Go to step 16 16 Turn the ignition switch to ON ID and check the same terminal for voltage to body ground 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 GRY LS REEE gn nnnnnnnnnonnrat Ts 2 s ms 29 0 28 29 e m a e m7 7 Wire side of female terminals Fig 65 Identifying Same Terminal For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there any voltage YES Repair short to power in the wire This short may have also damaged the climate control unit Repair the short to power before repla
121. mate control unit connector A 40P Check for continuity between climate control unit connector A 40P No 29 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P 81 on Te s Te Ts Te Tow LT cs 2 n o m v a2 o PUR Wire side of female terminals Fig 54 Identifying Continuity Between Climate Control Unit Connector 40 No 29 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX 15 there continuity YES Repair short to body ground in the wire between the climate control unit and the sunlight sensor NO Go to step 9 9 Check for continuity between climate control unit connector A 40P No 8 and No 29 terminals CLIMATE CONTROL UNIT CONNECTOR 40 n A 2 ire Wire side of female terminals Fig 55 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And No 29 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short in the wires between the climate control unit and the sunlight sensor NO Go to step 10 10 Reconnect the sunlight sensor 5P connector 11 Reconnect climate control unit connector A 40P 12 Test the sunlight sensor see SUNLIGHT SENSOR TEST Is the sunlight sensor OK YES Substitute a known good climate control unit and recheck If the symptom indication go
122. mate control unit connector A 40P Turn the ignition switch to ON II Measure the voltage between climate control unit connector A 40P No 6 and No 8 terminals and between climate control unit connector A 40P No 8 and No 26 terminals CLIMATE CONTROL UNIT CONNECTOR A 40 1 s e em s A7 LT a Wire side of female terminals Fig 119 Measuring Voltage Between Climate Control Unit Connector A 40P No 6 And No 8 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Is there about 5 V YES Replace the A C pressure sensor 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Check for loose wires or poor connections at climate control unit connector A 40P and at the A C pressure sensor 3P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B2980 OR DTC INDICATOR B AND WINDSHIELD DEFROST A SHORT IN THE A C PRESSURE SENSOR CIRCUIT 1 2 3 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B2980 or B and WINDSHIELD DEFROST indicated YES Go to step 5 NO Intermittent failur
123. n the rear blower motor relay and the blower motor NO Check for an open in the wire between the rear blower motor relay and body ground If the wire is OK check for poor ground at G503 see GROUND TO COMPONENTS INDEX DTC B1225 OR DTC INDICATOR A AND AUTO AN OPEN IN THE IN CAR TEMPERATURE SENSOR CIRCUIT l Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1225 or A and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the in car temperature sensor circuit Turn the ignition switch to LOCK 0 Remove the humidity in car temperature sensor see HUMIDITY IN CAR TEMPERATURE SENSOR REPLACEMENT and test it see HUMIDITY IN CAR TEMPERATURE SENSOR TEST Is the in car temperature sensor OK 2008 Acura MDX 2007 09 HVAC Climate Control MDX YES Go to step 7 NO Replace the humidity in car temperature sensor Disconnect climate control unit connector A 40P 8 Check for continuity between climate control unit connector A 40P No 5 terminal and the humidity in car temperature sensor 4P connector No 4 terminal CLIMATE CONTROL UNIT CONNECTOR 40P Wire side of female terminals 7
124. n with navigation unit A problem in the Climate control unit Signal error recirculation control linkage door or motor circuit Climate control unit lost Climate control unit Loss of communication communication with audio unit SYMPTOM TROUBLESHOOTING INDEX SYMPTOM TROUBLESHOOTING CHART Symptom Diagnostic procedure Also check for HVAC DTCs see GENERAL Rear mode control TROUBLESHOOTING Rear mode control motor circuit INFORMATION doors donot change oubleshooting see REAR MODE between ceiling vents CONTROL MOTOR CIRCUIT Blown ie NO Ain cool and floor vents TROUBLESHOOTING the under dash fuse relay box hot Cleanliness and tightness of all terminals HVAC DTCs see GENERAL TROUBLESHOOTING INFORMATION Blown fuse No 30 10 A in the under dash fuse relay box Blower heater Climate control unit troubleshooting see controls and A C CLIMATE CONTROL UNIT not work TROUBLESHOOTING Poor ground at G506 see GROUND TO COMPONENTS INDEX Cleanliness and tightness of all terminals e HVAC DTCs see GENERAL TROUBLESHOOTING 2008 Acura MDX 2007 09 HVAC Climate Control MDX INFORMATION e Blown fuse No 15 30 A in the relay block and No 30 10 Both fans do not run at Radiator and A C condenser fan low speed A n uh 222 PU el low speed with the circuit troubleshooting see RADIATOR lay b A C on but the AND A C CONDENSER FAN LOW compressor runs with SPEE
125. nd the climate control unit If it doesn t troubleshoot the DLC circuit see DLC CIRCUIT TROUBLESHOOTING Select HVAC CLIMATE CONTROL in the BODY ELECTRICAL menu Select DTCs in the HVAC CLIMATE CONTROL menu 7 Check for DTCs If any DTCs are indicated write down the DTCs then go to the indicated DTC troubleshooting If no DTCs are indicated refer to symptom troubleshooting NOTE e After troubleshooting clear the DTCs with the HDS e For specific operations refer to the user s manual that came with the HDS HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS de ES QN tA Make sure the ignition switch is LOCK 0 Connect the HDS to the data link connector DLC Turn the ignition switch to ON II Make sure the HDS communicates with the vehicle and the climate control unit If it doesn t troubleshoot the DLC circuit see DLC CIRCUIT TROUBLESHOOTING Select HVAC CLIMATE CONTROL in the BODY ELECTRICAL menu Select INSPECTION in the HVAC CLIMATE CONTROL menu 2008 Acura MDX 2007 09 HVAC Climate Control MDX 7 Select CLIMATE CONTROL SELF TEST in the INSPECTION menu 8 Check for DTCs If any DTCs are indicated write down the DTCs then go to the indicated DTC troubleshooting NOTE e After troubleshooting clear the DTCs with the HDS e For specific operations refer to the user s manual that came with the HDS HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS The climate control uni
126. nn s elu Te s TTs ss Ts L7 s e n 77 Wire side of female terminals 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 127 Identifying Same Terminal For Voltage To Ground Courtesy of AMERICAN HONDA MOTOR INC Does the voltage remain at about 5 V YES Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the component that caused the voltage drop DTC B2981 CLIMATE CONTROL UNIT LOST COMMUNICATION WITH NAVIGATION UNIT Ov Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS Check the DTCs Is DTC B2961 indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the navigation unit and climate control unit circuit Turn the ignition switch to LOCK 0 Disconnect navigation unit connector A 20P Disconnect climate control unit connector A 40P Check for continuity between the following terminals of climate control unit connector A 40P and navigation unit connector A 20P 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of fernale terminals NAVIGATION UNIT CONNECTOR A 20P Wire side of female terminals Fig 128 Identifying
127. nnect the 7P connector from the driver s air mix control motor NOTE Incorrectly applying power and ground to the driver s air mix control motor will damage it Follow the instructions carefully 2 Connect battery power to the No 1 terminal of the driver s air mix control motor and ground the No 2 2008 Acura MDX 2007 09 HVAC Climate Control MDX terminal the driver s air mix control motor should run and stop at Max Cool If it doesn t reverse the connections the driver s air mix control motor should run and stop at Max Hot When the driver s air mix control motor stops running disconnect battery power immediately DRIVER S AIR MIX CONTROL MOTOR Fig 172 Identifying Driver s Air Mix Control Motor Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC If the driver s air mix control motor did not run in step 2 remove it then check the driver s air mix control linkage and door for smooth movement e If the linkage and door move smoothly replace the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR REPLACEMENT e If the linkage or door sticks or binds repair them as needed e If the driver s air mix control motor runs smoothly go to step 4 Measure the resistance between the No 5 and No 7 terminals It should be between 4 2 to 7 8 kohms Reconnect the driver s air mix control motor 7P connector then turn the ignition switch to ON II Using the backprobe set measure the
128. not within the specifications replace the front power transistor NOTE Also check the front blower motor Front power transistor failure can be caused by a defective front blower motor FRONT POWER TRANSISTOR 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 170 Measuring Resistance Between No 3 And No 4 Terminals Of Front Power Transistor Courtesy of AMERICAN HONDA MOTOR INC 4 Carefully release the lock tab on the No 1 terminal RED A in the 4P connector then remove the terminal and insulate it from body ground JUMPER WIRE e x 7 To 12 V Power source on vehicle Fig 171 Identifying 4P Connector Terminal Courtesy of AMERICAN HONDA MOTOR CO INC 5 Reconnect the 4P connector to the front power transistor 6 Make sure the RED wire is completely isolated then supply 12 V to the No 1 cavity with a jumper wire 7 Turn the ignition switch to ON and check that the front blower motor runs e If the front blower motor does not run replace the front power transistor NOTE A faulty front blower motor can cause the front power transistor to fail If the front power transistor is replaced also check the front blower motor for binding and replace it if necessary e If the front blower motor runs the front power transistor is OK DRIVER S AIR MIX CONTROL MOTOR TEST NOTE Before testing check for HVAC DTCs see GENERAL TROUBLESHOOTING INFORMATION 1 Disco
129. ntifying Continuity Between Climate Control Unit B 14P And Rear Climate Control Panel 10P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 13 NO Repair open in the wire s between the climate control unit and the rear climate control panel Check for continuity between body ground and climate control unit connector B 14P No 11 and No 12 terminals individually CLIMATE CONTROL UNIT CONNECTOR B 14P ORN pi 9 Wire side of female terminals HOH Fig 108 Identifying Continuity Between Body Ground And Climate Control Unit Connector B 2008 Acura MDX 2007 09 HVAC Climate Control MDX 14P No 11 And No 12 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire s between the climate control unit and the rear climate control panel NO Go to step 14 14 Check for continuity between climate control unit connector B 14P No 11 and No 12 terminals CLIMATE CONTROL UNIT CONNECTOR B 14P Wire side of female terminals Fig 109 Identifying Continuity Between Climate Control Unit Connector B 14P No 11 And No 12 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short in the wires between the climate control unit and the rear climate control panel NO Substitute a known good rear climate control panel and recheck
130. nuity Between Climate Control Unit Connector A 40P No 8 And No 2 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 10 NO Repair open in the wire between the climate control unit and the sunlight sensor 10 Reconnect the sunlioht sensor 5P connector 11 12 2008 2007 09 HVAC Climate Control Reconnect climate control unit connector A 40 Test the sunlight sensor see SUNLIGHT SENSOR TEST Is the sunlight sensor OK YES Check for loose wires or poor connections at climate control unit connector A 40P and at the sunlight sensor 5P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the sunlight sensor see SUNLIGHT SENSOR REPLACEMENT DTC B1230 OR DTC INDICATOR F AND AUTO A SHORT IN THE SUNLIGHT SENSOR CIRCUIT Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1230 or F and AUTO indicated YES Go to step 5 NO Intermittent failure Turn the ignition switch to LOCK 0 Disconnect the sunlight sensor 5P connector Disconnect cli
131. o 6 And No 5 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair the short in the wires NO Go to step 12 12 Turn the ignition switch to ON II and measure the voltage between climate control unit connector B 14P No 5 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR B 14P Li 2131 ARAARA An m7 Wire side of female terminals Fig 98 Measuring Voltage Between Climate Control Unit Connector B 14P No 5 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there any voltage YES Repair short to power in the wire between the climate control unit and the rear air mix control motor This short may also damage the climate control unit Repair the short to power before replacing 2008 Acura MDX 2007 09 HVAC Climate Control MDX 13 14 15 16 the climate control unit NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit Turn the ignition switch to LOCK 0 and disconnect climate control unit connector A 40P Disconnect these items e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor Check for continuity between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A
132. o to step 30 NO Replace the fan control relay Turn the ignition switch to ON ID then set the A C button and fan control button ON Measure the voltage between the fan control relay 5P socket No 1 terminal and body ground FAN CONTROL RELAY 5P SOCKET Fig 147 Measuring Voltage Between Fan Control Relay 5P Socket No 1 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Go to step 32 NO Repair open in the wire between the A C condenser fan and the fan control relay Set the A C button and fan control button OFF then turn the ignition switch to LOCK 0 Disconnect the radiator fan 2P connector Check for continuity between the fan control relay 5P socket No 4 terminal and the radiator fan 2P connector No 2 terminal 35 36 37 2008 2007 09 HVAC Climate Control FAN CONTROL RELAY 5P SOCKET RADIATOR FAN 2P CONNECTOR Wire side of female terminals Fig 148 Identifying Continuity Between Fan Control Relay 5P Socket No 4 And No 2 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 35 NO Repair open in the wire between the fan control relay and the radiator fan Check for continuity between the radiator fan 2P connector No 1 terminal and body ground RADIATOR FAN 2P CONNECTOR BLK Wire side of female terminals Fig 149 Identifying Continuity Between Radiator Fan
133. od climate control unit and recheck If the symptom indication goes away replace the original climate control unit 20 While checking the same terminal for voltage to ground reconnect these items individually and note the voltage reading each time e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor CLIMATE CONTROL UNIT CONNECTOR A 40P 21 ez 23 oe 5 1m 2 s n i Wire side of female terminals Fig 77 Identifying Same Terminal For Voltage To Ground Courtesy of AMERICAN HONDA MOTOR CO INC Does the voltage remain at about 5 V YES Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the component that caused the voltage drop DTC B1238 OR DTC INDICATOR P AND AUTO A PROBLEM IN THE PASSENGER S AIR MIX CONTROL LINKAGE DOOR OR MOTOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 2008 Acura MDX 2007 09 HVAC Climate Control MDX Check for DTCs Is DTC B1238 or P and AUTO indicated YES Go to step 5 NO Intermittent failure check fo
134. on pressure mark until it intersects the vertical line NOTE The low side pressure and ambient air temperature should intersect in the shaded area Any measurements outside the area may indicate the need for further inspection Ambient Intake Temperature vs Low Side Suction Pressure HUMIDITY LEVEL 400 4 1 58 300 3 0 43 LOW SIDE SUCTION 200 PRESSURE 4 29 100 1 0 14 n gt 68 77 86 95 104 F 20 25 30 35 40 AMBIENT INTAKE TEMPERATURE Fig 231 Ambient Intake Temperature Vs Low Side Suction Pressure Graph Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX PRESSURE TEST PRESSURE TEST REFERENCE CHART Test results Related symptoms Probable cause Remedy Suction low pressure abnormally low After stopping A C compressor pressure drops about 196 kPa 2 0 kgf cm 28 psi quickly and then falls gradually Air in system e Clogged condenser or radiator fins Reduced or no airflow through A C condenser A C condenser or radiator fan not working properly Restricted flow of refrigerant in system Faulty A C compressor discharge valve Faulty A C compressor seal Line to A C condenser is excessively hot High and low pressures are balanced soon after stopping A C compressor Low side is higher than normal Faulty expansion
135. or a loose wire or poor connection at climate control unit connector A 40P If the connection is good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit 2008 Acura MDX 2007 09 HVAC Climate Control MDX 20 While checking the same terminal for voltage to ground reconnect these items individually and note the voltage reading each time e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor CLIMATE CONTROL UNIT CONNECTOR A 40 GRY 1 v LeTeTaTe e 7T e lo Tu Ton ww 77 IBI 20 24 oe gra HR Wire side of female terminals Fig 102 Identifying Climate Control Unit Connector A 40P Courtesy of AMERICAN HONDA MOTOR INC Does the voltage remain at about 5 V YES Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit NO Replace the component that caused the voltage drop DTC B1246 OR DTC INDICATOR H A PROBLEM IN THE REAR AIR MIX CONTROL LINKAGE DOOR OR MOTOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see
136. ound in the wire between the climate control unit and the driver s air mix control motor NO Go to step 11 Check for continuity between climate control unit connector A 40P No 6 and No 11 terminals CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 62 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 And No 11 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair the short in the wires NO Go to step 12 Turn the ignition switch to ON II and measure the voltage between climate control unit connector A 40P No 11 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40 m m w s a0 Wire side of female terminals Fig 63 Measuring Voltage Between Climate Control Unit Connector A 40P No 11 Terminal And 2008 Acura MDX 2007 09 HVAC Climate Control MDX Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there any voltage YES Repair short to power in the wire between the climate control unit and the driver s air mix control motor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original c
137. ous functions to see whether works properly 4 Run the self diagnostic function to confirm that there are no problems in the system see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS DUST AND POLLEN FILTER REPLACEMENT 1 Open the glove box Remove the glove box stop on right side then let the glove box hang down see GLOVE BOX REMOVAL INSTALLATION 2 Remove the dust and pollen filter assembly A from the blower unit 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 181 Identifying Dust And Pollen Filter Assembly Courtesy of AMERICAN HONDA MOTOR CO INC 3 Remove the filter A from the housing B and replace the filter Fig 182 Identifying Filter And Housin Courtesy of AMERICAN HONDA MOTOR INC 4 Install the filter in the reverse order of removal Make sure that there is no air leaking out of the blower unit BLOWER UNIT REMOVAL INSTALLATION 1 Remove the glove box see GLOVE BOX REMOVAL INSTALLATION 2 Remove the harness clips A the bolts and the glove box frame B Fig 183 Identifying Harness Clips And Glove Box Frame With Bolts Courtesy of AMERICAN HONDA MOTOR CO INC 3 Cut the plastic cross brace A in the glove box opening with diagonal cutters in the area shown and discard it 2008 Acura MDX 2007 09 HVAC Climate Control MDX Cut here Fig 184 Identifying Plastic Cross Brace Cutting Area Courtesy of AMERICAN HONDA MOTOR CO INC
138. r continuity between climate control unit connector A 40P No 8 and No 24 terminals 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40 Wire side of female terminals Fig 59 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And No 24 Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short in the wires between the climate control unit and the front evaporator temperature sensor NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1233 OR DTC INDICATOR J AND AUTO AN OPEN IN THE DRIVER S AIR MIX CONTROL MOTOR CIRCUIT 1 2 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1233 or J and AUTO indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the driver s air mix control motor circuit Turn the ignition switch to LOCK 0 Test the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR TEST Is the driver s air mix control motor OK YES Go to step 7 2008 Acura MDX 2007 09 HVAC Clim
139. r loose wires or poor connections on the passenger s air mix control motor circuit Turn the ignition switch to LOCK 0 Test the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR TEST Is the passenger s air mix control motor OK YES Go to step 7 NO Replace the passenger s air mix control motor see PASSENGER S AIR MIX CONTROL MOTOR REPLACEMENT or repair the passenger s air mix control linkage or door 7 Disconnect the passenger s air mix control motor 7P connector Disconnect climate control unit connector A 40P 9 Check for continuity between the following terminals of climate control unit connector A 40P and the passenger s air mix control motor 7P connector CLIMATE CONTROL UNIT CONNECTOR 40 Wire side of female terminals LTGRN YEL Q 112 s a 6 017818 elelelslel ell 2 2 L L LT GRN YEL PASSENGER S AIR MIX CONTROL MOTOR 7P CONNECTOR Wire side of female terminals Fig 78 Identifying Continuity Between Climate Control Unit A 40P And Passenger s Air Mix Control Motor 7P Connector Terminal 10 2008 Acura MDX 2007 09 HVAC Climate Control MDX Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 10 NO Repair open in the wire s between the climate control unit and the passenger s air mix control motor Check for continuity between bo
140. ra MDX 2007 09 HVAC Climate Control MDX Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1234 or and AUTO indicated YES Go to step 5 NO Intermittent failure Check for DTCs Are these DTCs also present B1237 or and AUTO and or B1245 or and or B2968 or A and WINDSHIELD DEFROST and or B2980 or B and WINDSHIELD DEFROST YES Go to step 13 NO Go to step 6 Turn the ignition switch to LOCK 0 Test the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR TEST Is the driver s air mix control motor OK YES Go to step 8 NO Replace the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR REPLACEMENT Disconnect the driver s air mix control motor 7P connector Disconnect climate control unit connector A 40P Check for continuity between body ground and climate control unit connector A 40P No 11 terminal CLIMATE CONTROL UNIT CONNECTOR A 40P PR e i eT e m m o 0 e we Wire side of female terminals Fig 61 Identifying Continuity Between Body Ground And Climate Control Unit Connector A 11 12 2008 Acura MDX 2007 09 HVAC Climate Control MDX 40P No 11 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body gr
141. re check for loose wires or poor connections on the rear evaporator temperature sensor circuit Turn the ignition switch to LOCK 0 Remove the rear evaporator temperature sensor see REAR EVAPORATOR TEMPERATURE SENSOR TEST and test it see REAR EVAPORATOR TEMPERATURE SENSOR TEST Is the rear evaporator temperature sensor OK YES Go to step 7 NO Replace the rear evaporator temperature sensor 7 Disconnect climate control unit connector B 14P Check for continuity between climate control unit connector B 14P No 6 terminal and the rear evaporator temperature sensor 2P connector No 2 terminal 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR 14 Wire side of female terminals LT BLU REAR EVAPORATOR TEMPERATURE SENSOR 2P CONNECTOR Wire side of female terminals Fig 27 Identifying Continuity Between Climate Control Unit Connector B 14P No 6 And No 2 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 9 NO Repair open in the wire between the climate control unit and the rear evaporator temperature sensor 9 Check for continuity between climate control unit connector A 40P No 8 terminal and the rear evaporator temperature sensor 2P connector No 1 terminal CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals RED REAR
142. roubleshooting see CLIMATE CONTROL UNIT TROUBLESHOOTING DTC B2979 OR DTC INDICATOR B AND WINDSHIELD DEFROST AN OPEN IN THE A C PRESSURE SENSOR CIRCUIT 1 Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 3 Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS 4 Check for DTCs Is DTC B2979 or B and WINDSHIELD DEFROST indicated YES Go to step 5 NO Intermittent failure check for loose wires or poor connections on the A C pressure sensor circuit Turn the ignition switch to LOCK 0 Disconnect the A C pressure sensor 3P connector Disconnect climate control unit connector A 40P WIA t Check for continuity between the following terminals of climate control unit connector A 40P and the A C pressure sensor 3P connector 2008 Acura MDX 2007 09 HVAC Climate Control MDX 10 11 CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals A C PRESSURE SENSOR 3P CONNECTOR Wire side of female terminals Fig 118 Identifying Continuity Between Climate Control Unit A 40P And A C Pressure Sensor 3P Connector Terminals Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Go to step 9 NO Repair open in the wire s between the climate control unit and the A C pressure sensor Reconnect cli
143. round If the wire is OK check for poor ground at G202 see GROUND TO COMPONENTS INDEX Jump the SCS line with the HDS NOTE This step must be done to protect the powertrain control module PCM from damage 7 Disconnect PCM connector A 49P Check for continuity between the fan control relay 5P socket No 3 terminal and PCM connector A 49P No 5 terminal FAN CONTROL RELAY 5P SOCKET zx meae ec PCM CONNECTOR 49 Terminal side of female terminals Fig 154 Identifying Continuity Between Fan Control Relay 5P Socket No 3 And No 5 Terminal Courtesv of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX Is there continuity YES Check for loose wires or poor connections at PCM connector A 49P No 5 terminal If the connections are good substitute a known good PCM and recheck If the symptom indication goes away replace the original PCM see PCM REPLACEMENT NO Repair open in the wire between the fan control relay and the PCM A C COMPRESSOR CLUTCH CIRCUIT TROUBLESHOOTING NOTE It is normal for the A C compressor to turn off under certain conditions oq sp such as low idle high engine coolant temperature hard acceleration or high low pressure e Do notuse this troubleshooting procedure if the fans are also inoperative with the A C on Refer to the SYMPTOM TROUBLESHOOTING INDEX Before doing any symptom troubleshootin
144. signed for the R 134a A C compressor Intermixing the recommended PAG refrigerant oil with any other refrigerant oil will result in A C compressor failure e All A C system parts A C compressor discharge line suction line evaporator A C condenser receiver dryer expansion valve O rings for joints are designed for refrigerant R 134a Do not exchange with R 12 parts e Use a halogen gas leak detector designed for refrigerant R 134a e R 12 and R 134a refrigerant servicing equipment are not interchangeable Use only a recovery recycling charging station that is U L listed and is certified to meet the requirements of SAE J2210 to service the R 134a air conditioning systems e Always recover refrigerant R 134a with an approved recovery recycling charging station before disconnecting any A C fitting HUMIDITY IN CAR TEMPERATURE SENSOR 2008 Acura MDX 2007 09 HVAC Climate Control MDX The humidity sensor consists of two sensors One sensor is for humidity detection and the other is for in car temperature detection When the climate control unit receives signals about the in car condition from the humidity sensor and judges that the humidity in the vehicle is very low the climate control unit reduces the compressor run time Engine power loss is kept to a minimum and fuel economy is increased TEMPERATURE INSPECTION SECTION Fig 13 Identifying Humidity In Car Temperature Sensor Component Courtesy of AMERICAN HONDA MOT
145. sor OK YES Go to step 7 NO Replace the rear evaporator temperature sensor 7 Disconnect climate control unit connector A 40P and B 14P 8 Check for continuity between climate control unit connector B 14P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR B 14P LT BLU TT lt sss T Wire side of female terminals 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 29 Identifying Continuity Between Climate Control Unit Connector B 14P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire between the climate control unit and the rear evaporator temperature sensor NO Go to step 9 Check for continuity between climate control unit connector A 40P No 8 terminal and climate control unit connector B 14P No 6 terminal CLIMATE CONTROL UNIT CONNECTOR 40P Wire side of female terminals naoogod a5 s se 1 Va LT BLU fele 415 6 CLIMATE CONTROL UNIT CONNECTOR B Wire side of female terminals Fig 30 Identifying Continuity Between Climate Control Unit Connector A 40P No 8 And No 6 Terminal Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short in the wires between the climate control unit and the rear evaporator temperature sensor NO
146. ssure sensor 3P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit 16 Turn the ignition switch to LOCK 0 and disconnect climate control unit connector A 40 17 Disconnect these items e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Hnmiditv in car temnerature sensor 2008 Acura MDX 2007 09 HVAC Climate Control MDX e A C pressure sensor 18 Check for continuity between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40 anonnos DD 1 20 o m e o v 77 Wire side of female terminals Fig 124 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there continuity YES Repair short to body ground in the wire NO Go to step 19 19 Turn the ignition switch to ON and check the same terminal for voltage to body ground CLIMATE CONTROL UNIT CONNECTOR A 40P lary 14 Lie Te Te Te Te L7Te s TeTe Te o Te TT 177 o a6 s 29 n m m n e m e v w 717 Wire side of female terminals Fig 125 Identifying Same Terminal For Voltage To Body Ground Courtesy of AMERICAN HONDA
147. stems should not be pressure tested or leak tested with compressed air Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers e Always disconnect the negative cable from the battery whenever replacing air conditioning parts e Keep moisture and dirt out of the system When disconnecting any lines plug or cap the fittings immediately don t remove the caps or plugs until just before you reconnect each line e Before connecting any hose or line apply a few drops of refrigerant oil to the O ring e When tightening or loosening a fitting use a second wrench to support the matching fitting e When discharging the system use an R 134a refrigerant recovery recycling charging station don t release refrigerant into the atmosphere A C REFRIGERANT OIL REPLACEMENT Recommended PAG oil DENSO ND OIL 8 e P N 38897 7 120 mL 4 fl oz P N 38899 7 01 40 mL 1 1 3 fl oz Add the recommended refrigerant oil in the amount listed if you replace any of the following parts e To avoid contamination do not return the oil to the container once dispensed and never mix it with other refrigerant oils e Immediately after using the oil reinstall the cap on the container and seal it to avoid moisture absorption e Do not spill the refrigerant oil on the vehicle it may damage the paint if it gets on the paint wash it off immediately A C condenser including Dryer Desiccant
148. t has a self diagnostic function To run the self diagnostic function do the following 1 Turn the ignition switch to LOCK 0 and then ON II 2 Press and hold the OFF button then press the RECIRCULATION CONTROL button five times within 10 seconds Release the OFF and RECIRCULATION CONTROL buttons then the self diagnostic begins NOTE e The blower motor will run at various speeds regardless of what the panel is displaying e If there is any problem in the system the system flashes 88 AUTO WINDSHIELD DEFROST or alternately flashes 88 AUTO WINDSHIELD DEFROST and one or more of the 14 segments A through P Refer to CHECKING FOR DTCS e If there are no problems detected the segments will not illuminate and the system will appear to be turned off DRIVER S TEMPERATURE T OR AUTOINDICATOR WINDSHIELD DEFROST INDICATOR AuTOGES AIC ONOEE eg AUTO BUTTON RECIRCULATION CONTROL BUTTON REAR WINDOW DEFOGGER Fig 10 Identifying Auto Button Driver Temperature Indicator And Rear Window Defogger Courtesy of AMERICAN HONDA MOTOR CO INC Canceling the Self diagnostic Function 2008 Acura MDX 2007 09 HVAC Climate Control MDX 3 Turn the ignition switch to LOCK 0 to cancel the self diagnostic function After completing the repair work run the self diagnostic function again to make sure that there are no other DTCs CHECKING FOR DTCS The temperature display indicates single or mul
149. the terminals YES Repair the short in the wires NO Go to step 12 Reconnect climate control unit connector A 40 P Turn the ignition switch to ON 1 and check the same terminals for voltage to body ground CLIMATE CONTROL UNIT CONNECTOR A 40P Hs TeTe Te oT Te Te oT Telese WHT x L T Qg T Wire side of female terminals Fig 33 Identifying Same Terminals For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there any voltage YES Repair short to power in the wire s between the climate control unit and the recirculation control motor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Check for loose wires or poor connections at climate control unit connector A 40P and at the recirculation control motor 7P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1223 OR DTC INDICATOR M A PROBLEM IN THE REAR BLOWER MOTOR CIRCUIT Clear the DTC with the HDS 2 Turn the ignition switch to LOCK 0 and then ON II 2008 Acura MDX 2007 09 HVAC Climate Control MDX Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNC
150. tiple DTCs If indicator segments A B C E G J M N AUTO and WINDSHIELD DEFROST are on at the same time there may be an open in the common ground wire If no DTCs are present the indicator remains blank DRIVER S TEMPERATURE INDICATOR AUTO INDICATOR WINDSHIELD DEFROST INDICATOR E tal AUTO Fig 11 Identifying A C Control Panel Courtesy of AMERICAN HONDA MOTOR CO INC DTC DRIVER S TEMPERATURE INDICATOR SEGMENT AUTO AND WINDSHIELD DEFROST INDICATOR CHART DTC Driver s Temperature Indicator Segment AUTO and Detection Item WINDSHIELD DEFROST Indicator An open in the in car temperature sensor circuit see DTC B1225 or DTC A and AUTO indicator A and AUTO An Open in the In car Temperature Sensor Circuit A short in the in car temperature sensor circuit see B1226 or DTC B and AUTO indicator B and AUTO A Short in the In car Temperature Sensor Circuit An open in the outside air temperature sensor circuit see DTC B1227 or C and AUTO DTC indicator C and AUTO An Open in the Outside Air Temperature Sensor Circuit A short in the outside air temperature sensor circuit see DTC B1228 or D and AUTO DTC indicator D and AUTO A Short in the Outside Air Temperature Sensor Circuit An open in the sunlight sensor circuit see DTC B1229 or DTC indicator E and AUTO An Open in the Sunlight Sensor Circuit A short in the sunlight sensor circuit see DTC B1230 or DTC indicator F and AUTO A Short in the Sunlight S
151. to step 9 NO Replace the relay block see REMOVAL AND INSTALLATION 9 Connect the A C compressor clutch relay 4P socket No 1 and No 2 terminals with a jumper wire A C COMPRESSOR CLUTCH RELAY 4P SOCKET r JUMPER WIRE PUR 10 11 12 13 14 15 16 17 2008 2007 09 HVAC Climate Control Fig 156 Identifying A C Compressor Clutch Relay 4P Socket No 1 And No 2 Terminals Courtesy of AMERICAN HONDA MOTOR CO INC Does the A C compressor clutch click YES Go to step 10 NO Go to step 19 Disconnect the jumper wire Turn the ignition switch to ON II Measure the voltage between the A C compressor clutch relay 4P socket No 4 terminal and body ground A C COMPRESSOR CLUTCH RELAY 4P SOCKET Fig 157 Measuring Voltage Between A C Compressor Clutch Relay 4P Socket No 4 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there battery voltage YES Go to step 13 NO Repair open in the wire between the No 30 10 A fuse in the under dash fuse relay box and the A C compressor clutch relay Turn the ignition switch to LOCK 0 Reinstall the A C compressor clutch relay Jump the SCS line with the HDS NOTE This step must be done to protect the powertrain control module PCM from damage Disconnect PCM connector A 49P Connect PCM connector A 49P No 13 terminal to body ground with a jumper wire 2008 Acura MDX 2007 09 H
152. trol MDX Fig 198 Identifying Adaptive Front Lighting Control Unit Connector And Harness Clip Courtesy of AMERICAN HONDA MOTOR INC 10 Disconnect the connectors A from the front mode control motor the passenger s air mix control motor the recirculation control motor and the front power transistor Remove the wire harness clips B Fig 199 Identifying Front Mode Control Motor Connector And Wire Harness Cli Courtesy of AMERICAN HONDA MOTOR INC 11 Disconnect the connectors A from the driver s air mix control motor and the front evaporator temperature sensor Remove the wire harness clips and the wire harness 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 200 Identifying Driver s Air Mix Control Motor Connector And Wire Harness Clips And Wire Harness Courtesy of AMERICAN HONDA MOTOR INC 12 Turn over the carpet Remove the wire harness clips A the rear heater duct mounting clips B and the rear heater duct C Fig 201 Identifying Wire Harness Clips Courtesy of AMERICAN HONDA MOTOR INC 13 Remove the mounting nuts Slide the blower heater unit A then remove the drain hose B and blower heater unit 14 15 16 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 202 Identifying Blower Heater Unit And Drain Hose With Mounting Nuts With Torque Specification Courtesy of AMERICAN HONDA MOTOR INC Remove t
153. tructions in B can diagnosis test mode A see TROUBLESHOOTING B CAN SYSTEM DIAGNOSIS TEST MODE A Clear the DTC with the HDS E CE Turn the ignition switch to LOCK 0 and then ON II Wait for 6 seconds or more Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check the DTCs Are DTCs B1205 and or B1206 or AUTO and or B1207 indicated YES Go to step 6 NO Intermittent failure check for loose wires or poor connections on the climate control unit connector A 40P Check for DTCs using the HDS Are any of the following DTCs indicated B1011 B1060 B2160 B1357 B1805 B1408 or B2157 YES Do the gauge control module input test see GAUGE CONTROL MODULE INPUT TEST NO Do the climate control unit troubleshooting see CLIMATE CONTROL UNIT 2008 Acura MDX 2007 09 HVAC Climate Control MDX TROUBLESHOOTING DTC B1213 OR DTC INDICATOR N AN OPEN IN THE REAR EVAPORATOR TEMPERATURE SENSOR CIRCUIT 1 2 3 Clear the DTC with the HDS Turn the ignition switch to LOCK 0 and then ON II Do the self diagnostic with the HDS see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITH THE HDS or climate control unit see HOW TO USE THE SELF DIAGNOSTIC FUNCTION WITHOUT THE HDS Check for DTCs Is DTC B1213 or N indicated YES Go to step 5 NO Intermittent failu
154. ttom of the A C condenser Remove the O ring B and the desiccant C 2 9 N m 0 3 kgf m 2 1 Ibf ft Fig 223 Identifying A C Condenser Cap O Ring And Desiccant With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 3 Install the receiver dryer in the reverse order of removal and note these items e Replace the O rings with new ones and apply a thin coat of refrigerant oil DENSO ND OIL 8 before installing them Be sure to use the correct O rings for HFC 134a R 134a to avoid leakage e Install the cap to the specified torque It is made of resin and can be easily stripped REFRIGERANT RECOVERY CAUTION e Air conditioning refrigerant or lubricant vapor can irritate your eyes nose or throat Be careful when connecting service equipment Do not breathe refrigerant or vapor NOTE e If accidental system discharge occurs ventilate the work area before 2008 Acura MDX 2007 09 HVAC Climate Control MDX resuming service e Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers 1 Connect an R 134a refrigerant recovery recycling charging station A to the high pressure service port B and the low pressure service port C as shown following the equipment manufacturer s instructions Pressure Service Port Courtesy of AMERICAN HONDA MOTOR CO INC 2 Measure the amount of refrigerant oil removed from the A C system after
155. uity YES Repair short to body ground in the wire s between the climate control unit and the front mode control motor NO Go to step 11 Check for continuity between climate control unit connector A 40P terminals as follows TERMINALS REFERENCE CHART From terminal To terminals 50 192 55 Is there continuity between of the terminals YES Repair the short in the wires 2008 Acura MDX 2007 09 HVAC Climate Control MDX NO Go to step 12 12 Turn the ignition switch to ON ID and check the same terminals for voltage to body ground CLIMATE CONTROL UNIT CONNECTOR 40 TT T Ts o 77 IGI WHT Wire side of female terminals Fig 82 Identifying Same Terminals For Voltage To Body Ground Courtesy of AMERICAN HONDA MOTOR INC Is there any voltage YES Repair short to power in the wire s between the climate control unit and the front mode control motor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Check for loose wires or poor connections at climate control unit connector A 40P and at the front mode control motor 7P connector If the connections are good substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit DTC B1240 OR DTC INDICATOR B A PROBLEM IN THE FRONT MODE CONTROL LINKAGE DOORS O
156. ulation control motor running as in step 2 check for continuity between the No 3 4 and 5 terminals and the No 7 terminal individually There should be continuity for a moment at each terminal as the motor moves past the switch s terminal is no continuity for a moment at each terminal replace the recirculation control motor see RECIRCULATION CONTROL MOTOR REPLACEMENT RECIRCULATION CONTROL MOTOR REPLACEMENT Remove the glove box see GLOVE BOX REMOVAL INSTALLATION 2 Disconnect the 7P connector A from the recirculation control motor B Remove the self tapping screws and the recirculation control motor from the heater unit Fig 179 Identifying Recirculation Control Motor And 7P Connector With Screws 2008 Acura MDX 2007 09 HVAC Climate Control MDX Courtesy of AMERICAN HONDA MOTOR INC 3 Install the motor in the reverse order of removal Make sure the pin on the motor is properly engaged with the linkage After installation make sure the motor runs smoothly CLIMATE CONTROL UNIT REMOVAL INSTALLATION 1 Remove the audio unit sce AUDIO UNIT REMOVAL INSTALLATION 2 Remove the self tapping screws bolts brackets A and the climate control unit B Fig 180 Identifying Self Tapping Screws Bolts Brackets And Climate Control Unit Courtesy of AMERICAN HONDA MOTOR CO INC 3 Install the control unit in the reverse order of removal After installation operate the vari
157. voltage between the No 3 and No 5 terminals Max Cool about 0 5 V Max Hot about 4 5 V If either the resistance or voltage readings are not as specified replace the driver s air mix control motor see DRIVER S AIR MIX CONTROL MOTOR REPLACEMENT DRIVER S AIR MIX CONTROL MOTOR REPLACEMENT l Remove the driver s dashboard undercover see DRIVER S DASHBOARD UNDERCOVER REMOVAL INSTALLATION Disconnect the 7P connector A from the driver s air mix control motor B Remove the self tapping screws and the driver s air mix control motor from the heater unit 2008 Acura MDX 2007 09 HVAC Climate Control MDX Fig 173 Identifying Driver s Air Mix Control Motor And 7P Connector With Screws Courtesy of AMERICAN HONDA MOTOR INC 3 Install the motor in the reverse order of removal Make sure the pin on the motor is properly engaged with the linkage After installation make sure the motor runs smoothly PASSENGER S AIR MIX CONTROL MOTOR TEST NOTE Before testing check for HVAC DTCs see GENERAL TROUBLESHOOTING INFORMATION 1 Disconnect the 7P connector from the passenger s air mix control motor NOTE Incorrectly applying power and ground to the passenger s air mix control motor will damage it Follow the instructions carefully 2 Connect battery power to the No 1 terminal of the passenger s air mix control motor and ground the No 2 terminal the passenger s air mix control motor should run and stop at
158. y make sure the recirculation control motor runs smoothly see RECIRCULATION CONTROL MOTOR REPLACEMENT Fig 188 Identifying Recirculation Control Motor Front Blower Motor And Dust And Pollen Filter Courtesy of AMERICAN HONDA MOTOR CO INC FRONT EXPANSION VALVE REPLACEMENT 1 Recover the refrigerant with a recovery recycling charging station see REFRIGERANT RECOVERY 2 Remove the front evaporator core see FRONT EVAPORATOR CORE REPLACEMENT 3 Remove the bolts then remove the front expansion valve A and O rings B Fig 189 Identifying Front Expansion Valve And O Rings Bolts With Torque Specification Courtesy of AMERICAN HONDA MOTOR CO INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX 4 Install the front expansion valve in the reverse order of removal and note these items e Replace the O rings with new ones at each fitting and apply a thin coat of refrigerant oil before installing them Be sure to use the correct O rings for HFC 134a R 134a to avoid leakage e Immediately after using the oil reinstall the cap on the container and seal it to avoid moisture absorption e Do not spill the refrigerant oil on the vehicle it may damage the paint if the refrigerant oil contacts the paint wash it off immediately e Make sure that there is no air leakage e Charge the system see SYSTEM CHARGING FRONT EVAPORATOR CORE REPLACEMENT 1 Recover the refrigerant with a recovery recycl
159. y ground 13 14 15 2008 Acura MDX 2007 09 HVAC Climate Control MDX CLIMATE CONTROL UNIT CONNECTOR A 40P Wire side of female terminals Fig 73 Measuring Voltage Between Climate Control Unit Connector A 40P No 30 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR CO INC Is there any voltage YES Repair short to power in the wire s between the climate control unit and the passenger s air mix control motor This short may also damage the climate control unit Repair the short to power before replacing the climate control unit NO Substitute a known good climate control unit and recheck If the symptom indication goes away replace the original climate control unit Turn the ignition switch to LOCK 0 and disconnect the climate control unit Disconnect these items e Driver s air mix control motor e Passenger s air mix control motor e Rear air mix control motor e Humidity in car temperature sensor e A C pressure sensor Check for continuity between climate control unit connector A 40P No 6 terminal and body ground CLIMATE CONTROL UNIT CONNECTOR A 40P w vTe Wire side of female terminals Fig 74 Identifying Continuity Between Climate Control Unit Connector A 40P No 6 Terminal And Body Ground Courtesy of AMERICAN HONDA MOTOR INC 2008 Acura MDX 2007 09 HVAC Climate Control MDX 16 17 18 19 Is there continuity YES
160. ystem must be evacuated 2008 Acura MDX 2007 09 HVAC Climate Control MDX A C SYSTEM TEST PERFORMANCE TEST CAUTION e Air conditioning refrigerant or lubricant vapor can irritate your eyes nose or throat Be careful when connecting service equipment e Do not breathe refrigerant or vapor The performance test will help determine if the A C system is operating within specifications NOTE e If accidental system discharge occurs ventilate the work area before resuming service e Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers 1 Connect an R 134a refrigerant recovery recycling charging station to the high pressure service port and the low pressure service port following the equipment manufacturer s instructions 2 Determine the relative humidity and air temperature 3 Open the glove box Remove the glove box stop on right side then let the glove box hang down see GLOVE BOX REMOVAL INSTALLATION 4 Insert a thermometer A in the center vent Fig 228 Identifying Thermometer Courtesy of AMERICAN HONDA MOTOR INC 5 Place a thermometer B near the blower unit s recirculation inlet duct 6 Test conditions e Avoid direct sunlight e Open hood e Open front doors 2008 Acura MDX 2007 09 HVAC Climate Control MDX e Set the temperature control switch to Max Cool the mode control switch to Vent and the recirculation control switc

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