Service Literature 12ACB SERIES UNITS
Contents
1. LIQUID LINE SERVICE VALVE DISCHARGE LINE FIGURE 1 12ACB UNIT CONTROL BOX s O gt DUAL CAPACITOR C12 COMPRESSOR CONTACTOR K1 TIMED OFF CONTROL TOC EARLY MODEL ail GROUNDING LUG 12ACB UNITS ONLY FIGURE 2 A Control Box Figure 2 12ACB units are not equipped with a 24V transformer All 24 VAC controls are powered by the indoor unit Refer to wiring diagram Electrical openings are provided under the control box cov er Field thermostat wiring is made to color coded pigtail connections 1 Compressor Contactor K1 The compressor is energized by a contactor located in the control box See figure 2 Single pole and two pole con tactors are used in 12ACB series units See wiring dia grams for specific unit K1 is energized by the indoor ther mostat terminal Y1 24V when thermostat demand is present A DANGER Electric Shock Hazard May cause injury or death Disconnect all remote electrical power supplies berore opening unit panel Unit may have multiple power supplies Some units are equipped with single pole contactors When unit is equipped with a single pole contactor line voltage is present at all components even when unit is not in operation 2 Dual Capacitor C12 The compressor and fan in 12ACB series units use per manent split capacitor motors2. TIMED OFF CONTROL O A ai T BLACK COMPRESSOR CONTACTORI z J j A Qa S Li GROUND KI I BI A LI j BLACK s OOA 208 230 60 1 YELLOW Lee i 208 230 60 RED ORANGE OOO DESCRIPTION COMPONENT GROUND EQUIPMENT BLACK COMPRESSOR MOTOR OQUTDOOR FAN CAPACI TOR DUAL CONTACTOR COMPRESSOR CONTROL TIMEN OFF 3 Nl Zx C TO 24 VAC POWER SOURCE 20 VA MINIMUN NEC CLASS 2 A NOTE Timed off control used on Dash 1 mod els only A OTE FOR USE WITH COPPER CONDUCTORS ONLY REFER TO UNIT RATING PLATE FOR MINIMUM CIRCUIT AMPACITY AND MAXIMUM OVER CURRENT PROTECTION SIZE WARNING ELECTRIC SHOCK HAZARD CAN CAUSE INJURY OR DEATH UNIT MUST BE GROUND IN ACCORDANCE WITH NATIONAL AND LOCAL CODES LINE VOLTAGE FIELD INSTALLED CLASS VOLTAGE FIELD INSTALLED NG DIAGRAM 9794 ENSING UNITS Z2ACB42 1P 2P LENNOX Gvstries rc WIR COOLING UNITS COND 2 ACB24 1P 2P 2ACB30 IP 2P 2ACB48 IP 2ACB36 1P 2P 2ACB60 IP COOLING UNITS B 1994 Lennox Industries Inc Litho U S A 12ACB 2 5 TON OPERATING SEQUENCE This is the sequence of operation for 12ACB 2 through 5 ton units The sequence is outlined by numbered steps which c
3. LENNOX UNITNFORMATION 12ACB Corp 9503 L1 Service Literature Revised 01 2002 12ACB SERIES UNITS The 12ACB is a residential split system condensing unit The series is designed for use with expansion valves TXV All 12ACB units utilize scroll compressors Information contained in this manual is intended for use by qualified service technicians only All specifications are subject to change This manual is divided into sections which discuss the major components refrigerant system charging proce dure maintenance and operation sequence I UNIT INFORMATION 12ACB condensing units are available in 2 2 1 2 3 3 1 2 4 and 5 ton capacities All major components indoor blower and coil must be matched according to Lennox recommen dations for the compressor to be covered under warranty Refer to the Engineering Handbook for approved system matchups SPECIFICATIONS Model No 12ACB24 12ACB30 12ACB36 1 15 21 1 41 2 5 11 1 40 1 15 21 1 41 2 15 11 1 40 1 15 21 1 41 2 15 11 1 40 Outer coil Net face area sq ft m2 1 5 44 0 51 1 14 50 1 3
4. 1385 3890 1835 3890 1835 1100 1085 1085 310 1 7 lbs 11 oz 3 49 kg 2 8 lbs 0 oz 36kg 10 Ibs 14 oz 4 93 kg 11 Ibs 0 oz 4 99 kg Liquid line in mm o d connection sweat 3 8 9 5 3 8 9 5 3 8 9 5 Suction line in mm o d connection sweat 7 8 22 2 7 8 22 2 1 1 8 28 6 Shipping weight Ibs kg 1 package 186 84 250 113 254 115 Refrigerant charge sufficient for 25 ft 7 6 m length of refrigerant lines ELECTRICAL DATA Model No Modano 12ACB24 12ACB30 12ACB36 12ACB42 12ACB48 12ACB60 Vigoaniaaau eee 208 230v 208 230v 208 230v 208 230v 208 230v 208 230v Ine Vonage Jala en 1ph 1ph 1ph 1ph 1ph 1ph Compressor peee f o e e 1 9 4 1 4 1 4 1 Condenser Coil Fan M tor Locked rotor amps Rec maximum fuse or circuit breaker size amps ES EESE SESES Minimum circuit ampacity Refer to National or Canadian Electrical Code manual to determine wire fuse and disconnect size requirements NOTE Extremes of operating range are plus 10 and minus 5 of line voltage Page 2 ll UNIT COMPONENTS Unit components are illustrated in figure 1 12ACB UNIT COMPONENTS OUTDOOR FAN MOTOR CONTROL SUCTION LINE SUCTION LINE SERVICE VALVE
5. 2ACB36 5P WITH NATIONAL AND LOCAL CODES Fe JEN BES e LINE VOLTAGE FIELD INSTALLED TOI CLASS iI VOLTAGE FIELD INSTALLED Supersedes Form No New Form No 533 470W 2000 Lennox Industries Inc Litho U S A 12ACB 2 5 TON OPERATING SEQUENCE This is the sequence of operation for 12ACB 2 through 5 ton units The sequence is outlined by numbered steps which correspond to circled numbers on the adjacent diagram NOTE The thermostat used may be electromechanical or electronic NOTE Transformer in indoor unit supplies power 24 VAC to the thermostat and outdoor unit controls COOLING 1 Cooling demand initiates at Y1 in the thermostat 2 24VAC from indoor unit Y1 energizes the timed off control TOC which energizes compressor contactor K1 pro vided the 5 minute delay is satisfied NOTE Later model units do not have the TOC Call for cooling goes directly to contactor K1 3 K1 1 N O closes energizing compressor B1 and outdoor fan motor B4 4 Compressor B1 and outdoor fan motor B4 begin immediate operation END OF COOLING DEMAND 5 Cooling demand is satisfied Terminal Y1 is de energized 6 Compressor contactor K1 is de energized 7 K1 1 opens and compressor B1 and outdoor fan motor B4 are de energized and stop immediately Page 11 12ACB 4 and 5 TON OPERATING SEQUENCE OUTDOOR FAN DUAL CAPACITOR TO 24 VAC POWER SOURCE 20 VA MINIMUN NEC CLASS 2 COMPRESSOR CONTACTOR GROUND
6. LINE SERVICE VALVE VALVE CLOSED RETAINING RING STEM CAP INSERT HEX WRENCH HERE SERVICE OUTLET TO COMPRESSOR SERVICE PORT CAP SCHRADER VALVE OPEN TO LINE SET WHEN VALVE IS CLOSED FRONT SEATED TO INDOOR COIL VALVE FRONT SEATED FIGURE 9 Page 6 B Service Valves Suction Line Ball Type Service Valve A ball type full service valve is used on all 12ACB units Valves are not rebuildable If a valve has failed it must be re placed A ball valve is illustrated in figure 10 The ball valve is equipped with a service port A schrader valve is factory installed A service port cap is supplied to pro tect the schrader valve from contamination and assure a leak free seal SUCTION LINE BALL TYPE SERVICE VALVE VALVE OPEN USE ADJUSTABLE WRENCH ROTATE STEM CLOCKWISE 90 TO CLOSE ROTATE STEM COUNTER CLOCKWISE 90 TO OPEN STEM CAP OUTLET TO COMPRESSOR SERVICE PORT x CAP we X SCHRADER CORE FIGURE 10 IV CHARGING The unit is factory charged with the amount of R 22 refrig erant indicated on the unit rating plate This charge is based on a matching indoor coil and outdoor coil with a 20 foot 6 1 m line set For varying lengths of line set refer to table 3 for refrigerant charge adjustment A blank space is provided on the unit rating plate to list actual field charge A IMPORTANT If line length is greater than 20 feet 6 1 m add this amount If line length is less tha
7. LUG GROUND TO 24 VAC GROUND POWER SOURCE CHEKA 20 VA MINIMUN NEC CLASS 2 is PURPLE DESCRIPTION COMPONENT B OMPR NOTE B4_ MOTOR ZAFOR USE WITH COPPER CONDUCTORS ICl2__ CAPACI TOR DUAL ONLY REFER TO UNIT RATING IKI ICONTACTOR COMPRESSOR PLATE FOR MINIMUM CIRCUIT AMPACITY AND MAXIMUM OVER I LENNDXe KOO ANG UNA TPs WARNING CURRENT PROTECTION SIZE ELECTRIC SHOCK HAZARD CAN CAUSE INJURY OR DEATH UNIT MUST BE GROUND IN ACCORDANCE AE WITH NATIONAL AND LOCAL CODES J e LINE VOLTAGE FIELD INSTALLED ne de CLASS VOLTAGE FIELD INSTALLED New Form No 533 471W 2000 Lennox Industries Inc Litho U S A 12ACB 2 5 TON OPERATING SEQUENCE This is the sequence of operation for 12ACB 2 through 5 ton units The sequence is outlined by numbered steps which correspond to circled numbers on the adjacent diagram NOTE The thermostat used may be electromechanical or electronic NOTE Transformer in indoor unit supplies power 24 VAC to the thermostat and outdoor unit controls COOLING 1 Cooling demand initiates at Y1 in the thermostat 2 24VAC from indoor unit Y1 energizes the timed off control TOC which energizes compressor contactor K1 pro vided the 5 minute delay is satisfied NOTE Later model units do not have the TOC Call for cooling goes directly to contactor K1 3 K1 1 N O closes energizing compressor B1 and outdoor fan motor B4 4 Compressor B1 and outdoor fan motor B4 b
8. checking charge A schrader valve is factory installed A service port cap is supplied to protect the schrader valve from contamination and serve as the primary leak seal NOTE Always keep valve stem caps clean To Access Schrader Port 1 Remove service port cap with an adjustable wrench 2 Connect gauge to the service port 3 When testing is completed replace service port cap Tighten finger tight then an additional 1 6 turn To Open Liquid or Suction Line Service Valve 1 Remove stem cap with an adjustable wrench 2 Using service wrench and 5 16 hex head extension back the stem out counterclockwise until the valve stem just touches the retaining ring 3 Replace stem cap and tighten finger tight then tighten an additional 1 6 turn A DANGER Do not attempt to backseat this valve Attempts to backseat this valve will cause snap ring to explode from valve body under pressure of refrigerant Personal injury and unit damage will result To Close Liquid or Suction Line Service Valve 1 Remove stem cap with an adjustable wrench 2 Using service wrench and 5 16 hex head extension turn stem clockwise to seat the valve Tighten firmly 3 Replace stem cap Tighten finger tight then tighten an additional 1 6 turn LIQUID LINE SERVICE VALVE VALVE OPEN INSERT HEX STEM CAP SERVICE PORT OUTLET TO COMPRESSOR W fi N SERVICE gee PORT CAP TO INDOOR COIL SCHRADER VALVE LIQUID
9. is internaly built and me chanically prevents the compressor from turning back wards 4A DANGER DO NOT ATTEMPT TO REPAIR THIS CONTROL UN SAFE OPERATION WILL RESULT IF THE CONTROL IS FOUND TO BE INOPERATIVE SIMPLY REPLACE THE ENTIRE CONTROL B Compressor SCROLL COMPRESSOR SUCTION FIGURE 3 All 12ACB units utilize a scroll compressor The scroll com pressor design is simple efficient and requires few moving parts A cutaway diagram of the scroll compressor is shown in figure 3 The scrolls are located in the top of the compressor can and the motor is located just below The oil level is imme diately below the motor The scroll is a simple compression concept centered around the unique spiral shape of the scroll and its inherent properties Figure 4 shows the basic scroll form Two identical scrolls are mated together forming concentric spiral shapes figure 5 One scroll remains stationary while the other is allowed to or bit figure 6 Note that the orbiting scroll does not rotate or turn but merely orbits the stationary scroll NOTE During operation the head of a scroll compressor may be hot since it is in constant contact with discharge gas SCROLL FORM FIGURE 4 CROSS SECTION OF SCROLLS DISCHARGE STATIONARY SCROLL WK PRESSURE S gt Ny Ye SFFISFFIFSS ctititithk SSS Oe eee SSS G y Z y j SS T T i Ny so H N N Y TIPS SEALED BY ORBITING SCRO
10. vacuum pump and disconnect from gauge man ifold Attach an upright nitrogen drum to center port of gauge manifold and open drum valve slightly to purge line at manifold Break vacuum in system with nitro gen pressure by opening manifold high pressure valve Close manifold high pressure valve to center port 4 Close nitrogen drum valve and disconnect from gauge manifold center port Release nitrogen pres sure from system 5 Connect vacuum pump to gauge manifold center port Evacuate system through manifold service valves until vacuum in system does not rise above 5mm of mercury absolute pressure or 500 microns within a 20 minute period after stopping vacuum pump 6 After evacuation is complete close manifold center port and connect refrigerant drum Pressurize system slightly with refrigerant to break vacuum D Charging If the system is completely void of refrigerant the recom mended and most accurate method of charging is to weigh the refrigerant into the unit according to the total amount shown on the unit nameplate Also refer to the SPECIFI CATIONS tables on pages 1 and 2 If weighing facilities are not available or if unit is just low on charge the following procedure applies Expansion Valve Systems The following procedures are intended as a general guide for use with expansion valve systems only For best results in door temperature should be between 70 F and 80 F 21 1 C and 26 7 C Outdoor temperature s
11. 5 1 14 50 1 35 2 5 40 0 50 2 14 40 1 33 2 14 40 1 33 Tube diameter in mm amp no of rows 5 16 8 1 37 5 16 8 5 16 8 2 Fins per inch 22 866 2 866 22 866 Motor hp W 1 6 124 1 6 124 1 6 124 Condenser Inner coil Coil ear e Cfm L s 2500 1180 2450 1155 2450 1155 1100 1100 1100 C E E 1 5 lbs 8 oz 2 49 kg 1 7 lbs 3 oz 3 26 kg 1 7 lbs 4 oz 3 29 kg Refrigerant charge furnished HCFC 22 2 5 lbs 0 oz 2 26 kg 2 6 lbs 8 oz 2 95 kg 2 6 lbs 10 oz 3 0 kg Liquid line in mm o d connection sweat line in mm o d connection sweat 3 8 9 5 3 8 9 5 3 8 9 5 Suction line in mm o d connection sweat eS 3 4 19 1 3 4 19 1 7 8 22 2 Shipping weight Ibs kg 1 package 155 70 175 79 180 187 Refrigerant charge sufficient for 25 ft 7 6 m length of refrigerant lines T ean Page 1 1996 Lennox Industries Inc ublications SPECIFICATIONS continued Model No overo Inner coil ea rere Diameter in mm amp no of blades erate Fan Net face area sq ft m2 Condenser Coil Refrigerant charge furnished HCFC 22 12ACB42 12ACB48 12ACB60 21 11 1 96 21 11 1 96 20 31 1 89 20 31 1 89 1 15 21 1 41 2 15 11 1 40 1 14 50 1 35 2 14 40 1 33 2930
12. COIL ENTERING AIR TEMPERATURE SUC 10 PSIG LIQ 10 PSIG LIQ 95 F 52 8 C These are typical pressures only Indoor evaporator match up indoor air quality and evaporator load will cause the pressures to vary E Oil Charge Refer to table 2 on page 4 V MAINTENANCE At the beginning of each cooling season the system should be cleaned as follows A Outdoor Unit 1 Clean and inspect condenser coil Coil may be flushed with a water hose 2 Visually inspect all connecting lines joints and coils for evidence of oil leaks NOTE Outdoor fan motors are permanently lubricated 12ACB24 12ACB30 12ACB36 12ACB42 SUC 10 SUC 10 PSIG LIQ SUC 10 PSIG LIQ 10 PSIG 2 7 20 0 B Indoor Coil 1 Clean coil if necessary 2 Check connecting lines and coil for evidence of oil leaks 3 Check condensate line and clean if necessary C Indoor Unit 1 Clean or change filters 2 Bearings are pre lubricated and need no further oil ing 3 Check all wiring for loose connections 4 Check for correct voltage at unit 5 Check amp draw on blower motor Unit nameplate Actual Page 9 VI WIRING DIAGRAMS AND SEQUENCE OF OPERATION 12ACB 2 THROUGH 5 TON OPERATING SEQUENCE OUTDOOR FAN oO QH DUAL CAPACITOR TO 24 VAC POWER SOURCE 20 VA MINIMUN NEC CLASS 2 PURPLE BLACK ORANGE RED YELLOW COMPRESSOR
13. LL DISCHARGE PRESSURE FIGURE 5 The counterclockwise orbiting scroll draws gas into the outer crescent shaped gas pocket created by the two scrolls figure 6 1 The centrifugal action of the orbiting scroll seals off the flanks of the scrolls figure 6 2 As the orbiting motion contin ues the gas is forced toward the center of the scroll and the gas pocket becomes compressed figure 6 3 When the compressed gas reaches the center it is discharged vertically into a chamber and discharge port in the top of the compres sor figure 5 The discharge pressure forcing down on the top scroll helps seal off the upper and lower edges tips of the scrolls figure 5 During a single orbit several pockets of gas are compressed simultaneously providing smooth continuous compression The scroll compressor is tolerant to the effects of liquid return If liquid enters the scrolls the orbiting scroll is allowed to sepa rate from the stationary scroll The liquid is worked toward the center of the scroll and is discharged If the compressor is re placed conventional Lennox cleanup practices must be used Page 4 SUCTION Ro A SUCTION POCKET ORBITING SCROLL STATIONARY SCROLL SUCTION SUCTION pe INTERMEDIATE PRESSURE GAS 2 CRECENT SHAPED GAS POCKET FLANKS SEALED A BY CENTRIFIGUAL FORCE 2 MOVEMENT OF ORBIT 3 HIGH PRESURE GAS SUCTION D DISCHARGE POCKET FIGURE 6 Due to its efficiency the scr
14. The capacitor is located inside the unit control box see figure 2 A single dual capacitor C12 is used for both the fan motor and the compressor see unit wiring diagram The fan side and the compressor side of the capacitor have different MFD ratings See table 1 for dual capacitor ratings TABLE 1 12ACB C12 DUAL CAPACITOR RATING Unit Terminal MFD VAC 12ACB24 12ACB30 12ACB36 42 12ACB48 12ACB60 3 Timed Off Control TOC 12ACB models built prior to July1996 are equipped with a timed off control The time delay is electrically connected between thermostat terminal Y and the compressor con tactor Between cycles the compressor contactor is delayed for 5 minutes 2 minutes At the end of the delay the compressor is allowed to energize When thermostat demand is satisfied the time delay opens the circuit to the compressor contactor coil and the compressor is de ener gized Without the time delay it would be possible to short cycle the compressor A scroll compressor when short cycled can run backward if head pressure is still high It does not harm a scroll compressor to run backward but it could cause a nuisance tripout of safety limits internal overload Page 3 For this reason if a TOC delay should fail it must be re placed Do not bypass the control Later model scroll com pressors have an arrest feature which eliminates the need for the TOC The arrest feature
15. de detector Add a small amount of R22 3 to 5 psig 20kPa to 34kPa then pressurize with nitrogen to 150 psig 4 Release nitrogen pressure from the system correct any leaks and recheck A CAUTION When using dry nitrogen a pressure reducing reg ulator must be used to prevent excessive pres sure in gauge manifold connecting hoses and within the system Regulator setting must not ex ceed 150 psig 1034 kpa Failure to use a regulator can cause equipment failure resulting in injury Page 7 C Evacuating the System 1 Attach gauge manifold Connect vacuum pump with vac uum gauge to center port of gauge manifold With both manifold service valves open start pump and evacuate indoor coil and refrigerant lines A IMPORTANT A temperature vacuum gauge mercury vacuum U tube or thermocouple gauge should be used The usual Bourdon tube gauges are not accurate enough in the vacuum range A IMPORTANT The compressor should never be used to evacu ate a refrigeration or air conditioning system 2 Evacuate the system to 29 inches 737mm vacuum During the early stages of evacuation it is desirable to stop the vacuum pump at least once to determine if there is a rapid loss of vacuum A rapid loss of vacuum would indicate a leak in the system and a repeat of the leak testing section would be necessary 3 After system has been evacuated to 29 inches 737mm close gauge manifold valves to center port stop
16. egin immediate operation END OF COOLING DEMAND 5 Cooling demand is satisfied Terminal Y1 is de energized 6 Compressor contactor K1 is de energized 7 K1 1 opens and compressor B1 and outdoor fan motor B4 are de energized and stop immediately Page 12
17. from the fan guard by removing the four nuts found on the top panel Drip loops should be used in wiring when servicing motor See figure 8 if condenser fan motor re placement is necessary A DANGER Make sure all power is disconnected before beginning electrical service procedures CONDENSER FAN MOTOR AND COMPRESSOR ACCESS Remove 7 screws FAN GUARD _ REMOVE 7 SCREWS SECURING FAN GUARD REMOVE FAN GUARD FAN ASSEMBLY FIGURE 7 Remove 4 nuts ALIGN FAN HUB FLUSH WITH END OF SHAFT FIGURE 8 Page 5 lll REFRIGERANT SYSTEM A Plumbing Field refrigerant piping consists of liquid and suction lines from the condensing unit sweat connections to the indoor evaporator coil flare or sweat connections Use Lennox L10 flare or L15 sweat series line sets as shown in table 1 TABLE 1 Length of Liquid Line Suction Line Lines Outside Dia Outside Dia L10 or te om i me tf Model No l L10 41 20 L15 41 20 pg L10 41 30 L15 41 30 gpg 12ACB24 12ACB30 L10 41 40 L15 41 40 L10 41 50 L15 41 50 L10 65 30 L15 65 30 pgg 12ACB36 12ACB42 T 40 12 3 8 95 7 8 222 12ACB48 L10 65 50 L15 65 50 12ACB60 Not available 1 118 Field fabricate The liquid and suction line service valves figures 9 and 10 and gauge ports are accessible from outside the unit The valve is equipped with a service port The service ports are used for leak testing evacuating charging and
18. hould be 60 F 15 6 C or above Slight variations in charging temperature and pressure should be expected Large variations may indicate need for further servicing A IMPORTANT The following procedure requires accurate read ings of ambient outdoor temperature liquid temperature and liquid pressure for proper charging Use a thermometer with accuracy of 2 F 1 1 C and a pressure gauge with accuracy of 5 PSIG 34 5 kPa APPROACH METHOD TXV SYSTEMS Ambient Temperature of 60 F 16 C or Above NOTE It may be necessary to restrict air flow in order to reach liquid pressures in the 200 250 psig range which are required for checking charge The indoor temperature should be above 70 F 21 C Block equal sections of air intake panels moving obstructions sideways until liquid pressures in the 200 250 psig range are reached 1 Connect gauge manifold Connect an upright R 22 drum to center port of gauge manifold 2 Record outdoor air ambient temperature 3 Operate indoor and outdoor units in cooling mode Allow outdoor unit to run until system pressures sta bilize 4 Make sure thermometer well is filled with mineral oil before checking liquid line temperature 5 Place thermometer in well and read liquid line tem perature Liquid line temperature should be warmer than the outdoor air temperature Table 4 shows how many degrees warmer the liquid line temperature should be Add refrigerant to lower liquid
19. line temperature Recover refrigerant to raise the liquid line tempera ture Add refrigerant slowly as the unit approaches the correct temperature This will allow the refrigerant to stabilize allowing the correct temperature to be read 6 When unit is properly charged liquid line pres sures should approximate those in tables 5 and 6 Page 8 TABLE 4 APPROACH METHOD 12ACB 1 APPROACH TEMPERATURE LIQUID LINE F OUTDOOR AMBIENT F 9 F 5 0 C 12 F 6 7 C 11 F 6 1 C Model 12ACB24 12ACB30 12ACB36 12ACB42 12ACB48 12ACB60 Voe ua ime P ourooor an LIQUID LINE F OUTDOOR AMBIENT F 12ACB24 10 F 5 5 C 12ACB36 12ACB42 8 F 4 4 C 7 F 3 8 C 8 F 4 4 C TABLE 5 12ACB 1 SERIES UNITS NORMAL OPERATING PRESSURES 12ACB24 12ACB30 OUTDOOR COIL 12ACB36 12ACB42 12ACB48 12ACB60 LIQ SUC 10 10 PSIG PSIG LIQ 10 PSIG ENTERING AIR TEMPERATURE SUC LIQ SUC 10 10 10 PSIG PSIG PSIG 65 F 18 3 C 148 75 158 73 153 71 75 F 23 92 C 174 76 183 74 178 73 85 F 31 2 C 205 78 213 75 208 74 95 F 31 2 C 236 79 247 77 240 75 105 F 31 2 C 269 80 282 78 276 77 These are typical pressures only Indoor evaporator match up indoor air quality and evaporator load will cause the pressures to vary TABLE 6 12ACB 2 SERIES UNITS NORMAL OPERATING PRESSURES OUTDOOR
20. n 20 feet 6 1 m subtract this amount LIQUID LINE SET DIAMETER 1 4 in 6 mm 5 16 in 8mm Ounce per 5 foot ml per mm adjust from 20 foot 6 1m line set 1 ounce per 5 feet 30 ml per 1524 mm 2 ounce per 5 feet 60 ml per 1524 mm If line set is greater than 20 ft 6 1m add this amount If line set is less than 20 feet 6 1 m subtract this amount Units are designed for line sets up to 50 feet 15 2 m Consult Lennox Refrigerant Piping Manual for line sets over 50 feet 15 2 m A Pumping Down System A CAUTION Deep vacuum operation operating compressor at 0 psig or lower can cause internal fusite arcing resulting in a damaged or failed compressor This type of damage will result in denial of warranty claim The system may be pumped down when leak checking the line set and indoor coil or making repairs to the line set or indoor coil 1 Attach gauge manifold 2 Front seat close liquid line valve 3 Start outdoor unit 4 Monitor suction gauge Stop unit when 0 psig is reached 5 Front seat close suction line valve B Leak Testing To Be Done Before Evacuating 1 Attach gauge manifold and connect a drum of dry nitro gen to center port of gauge manifold 2 Open high pressure valve on gauge manifold and pressurize line set and indoor coil to 150 psig 1034 kPa 3 Check lines and connections for leaks NOTE The preferred method is to use an electronic leak or Hali
21. oll compressor is capable of draw ing a much deeper vacuum than reciprocating compres sors Deep vacuum operation can cause internal fusite arcing resulting in damaged internal parts and will result in compressor failure Never use a scroll compressor for evacuating or pumping down the system This type of damage can be detected and will result in denial of warranty claims Table 2 shows the specifications of compressors used in 12ACB series units TABLE 2 12ACB COMPRESSOR SPECIFICATIONS Unit___ __ MAN MODEL Voltage Phase LRA RLA Oil fl oz 12ACB24 COP ZR22K3 PFV 208 230 1 56 38 12ACB30 COP ZR28K3 PFV 208 230 1 73 38 1 12ACB36 COP ZR34K3 PFV 208 230 88 42 COP ZR40K3 PFV 2 104 18 0 42 7 12ACB42 08 230 1 The scroll compressor is quieter than a reciprocating com pressor however the two compressors have much different sound characteristics The sounds made by a scroll com pressor do not affect system reliability performance or indi cate damage C Condenser Fan Motor All units use single phase PSC fan motors which require a run capacitor In all units the condenser fan is controlled by the compressor contactor ELECTRICAL DATA tables in this manual show specifi cations for condenser fans used in 12ACBs Access to the condenser fan motor on all units is gained by removing the seven screws securing the fan assem bly See figure 7 The condenser fan motor is removed
22. orrespond to circled numbers on the adjacent diagram NOTE The thermostat used may be electromechanical or electronic NOTE Transformer in indoor unit supplies power 24 VAC to the thermostat and outdoor unit controls COOLING 1 Cooling demand initiates at Y1 in the thermostat 2 24VAC from indoor unit Y1 energizes the timed off control TOC which energizes compressor contactor K1 pro vided the 5 minute delay is satisfied NOTE Later model units do not have the TOC Call for cooling goes directly to contactor K1 3 K1 1 N O closes energizing compressor B1 and outdoor fan motor B4 4 Compressor B1 and outdoor fan motor B4 begin immediate operation END OF COOLING DEMAND 5 Cooling demand is satisfied Terminal Y1 is de energized 6 Compressor contactor K1 is de energized 7 K1 1 opens and compressor B1 and outdoor fan motor B4 are de energized and stop immediately Page 10 12ACB 2 THROUGH 3 1 2 TON OPERATING SEQUENCE ar SETCE TO 24 VAC POWER 20 VA MINIMUN NEC CLASS 2 f NEC CLASS 2 DESCRIPTION _ __ PURPLE COMPONENT NOTE BL COMPRESSOR FOR USE WITH COPPER CONDUCTORS B4 __ MOTOR OUTDOOR FAN ONLY REFER TO UNIT RATING C12 CAPACITOR PLATE FOR MINIMUM CIRCUIT DUAL IKI I CONTACTOR COMPRESSOR AMPACITY AND MAXIMUM OVER CURRENT PROTECTION SIZE LENNOX WARNING ELECTRIC SHOCK HAZARD CAN CAUSE INJURY OR DEATH UNIT MUST BE GROUNDED IN ACCORDANCE 2ACB24 6P
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