Carrier 38AB054 User's Manual
Contents
1. HINGED CONTROL BOX COVERS 38AB054 064 084 9 BOTH SIDES BOTH SIDES SPACE FOR SERVICE U E gt AIR FLOW THR OEEO CONDENSER Certified dimension drawings are available on request Fig 1 Dimensions Carrier Corporation 1972 Form 38AD 6Sl RIGGING Lift unit at points G H J and K Fig 2 Use eyebolts and washers supplied in parts package Do not sling unskidded unit Skidded unit may be slung provided sling does not contact unit sides Do not roll unskidded unit on pipes or wooden pilings RRO RD asenne vanana oaas Fig 2 Weight Distribution and Lifting Points Table 2 Weight Distribution WEIGHT Ib _ Leg Location UNIT 38AD024 38AD028 38AD034 38AD044 38AB054 38AB064 38AB084 SKID REMOVAL Remove the four bolts each section holding top frame in place and lift frame from unit 38AD024 thru 044 and 38AB054 064 units Compressor with coil Section Raise and block up one side of unit 8 inches Remove the three exposed hold down bolts from base skid Lower unit and repeat on opposite side Coil only Section 38AB054 064 and 084 Raise and block up one end of unit 8 inches Remove the two exposed hold down bolts from base skid Lower unit and repeat on opposite end ERECTING AND INTEGRATING ONE UNIT Position Units 38AD028 044 and 38AB054 064 084 so air flow is unrestricted on all sides and on top Fig 1 38AD024 0342. 5 and braze as indicated Electrically connect unit control box and junc tion box on coil only section by using flexible fan conduit furnished in the unit Use the mating quick connect polarized plugs furnished in the two sections to make the wire connections Motormaster 32 Series Head Pressure Controller Refer to MOTORMASTER Instructions shipped with this accessory plus the following information Control box and sensor location is shown in Fig 6 Electrical connections are shown in Fig 7 Refer to unit label diagram as required On 200 208 and 230 volt units outdoor fan motor no 1 OFM located nearest the compressor may be used with MOTORMASTER without modification For 460 and 575 volt units refer to Table 4 for field supplied components needed with MOTORMASTER Fig 5 Refrigerant Connections Fig 6 MOTORMASTER Control Box and Sensor Location 200 208 AND 230 VOLT UNITS CONTACTOR LT BLK 200 208 230 7 2o MASTER STIRT CONTROLLER 200 230 V RATED CONTROLLER Use 230 volt controlier with 200 208 or 230 volt motors Fig 7 Motormaster Electrical Connections Table 4 Components Required for MOTORMASTER Use RUN TRANS MODELI CAPACITOR FORMER gt 600 THTOTAH9S1 IHC46VL 220 or 38AD028 38AD034 pias ses A 38AB0544 100 HC96LH030 HTOVAH954 38AD044 HC52T E230 38AB064 38AB084 REDUCING UPPER COIL G
3. UPPER COIL A SUCTION LINE TO COMPRESSOR LOWER COIL lt A REDUCING COUPLING OIL RETURN EVAPORATOR PIPING NON FREE DRAINING COIL E450 amp 90 STREET ELLS D gt AIR FLow COMPRESSOR ABOVE COMPRESSOR ABOVE SUCTION Ld BELOW DOUBLE RISER COMPRESSOR NOTES 2 Dasused in 8D etc indicates the pipe diameter size as a measure of length 1 Lower split first on fast off 273 3 TXVE indicates Thermostatic Expansion Valve Equalizer Connection Fig 8 Typical Piping Connections for Face Split Coils 4 38AD028 034 UNITS Fig 9 Recommended Filter Drier s and Sight Glass Locations Table 5 Filter Drier Replacement Parts and Data FILTER DRIER Conn Replacement 38AD024 KH43LE123 Same 38AD028 4 KH43LE121 Same 0 38AD034 j KH43LE121 Same 0 38AD044 KH49EA030 KH29E Z050 2 38AB054 KH49EA120 KH29E Z050 2 38AB064 KH4A9EA120 KH29E Z050 2 38AB084 KH49E A040 KH29E Z050 3 Replaceable cores only Install field supplied thermostatic expansion valve in liquid line ahead of each evaporator section For two step cooling the solenoids used must be wired to be opened by control from a two step thermostat For example two solenoids may be used with three TXV s one of the solenoids serving a liquid line feeding two of the TXV s When three solenoids are used with three TXV s two of the solenoids must be tied in parallel with th
4. Wire liquid line solenoid as shown LOW VOLTAGE REMOTE CONTROL Install field supplied accessories as shown in Fig 11 or Fig 12 for either two step cooling or two step cooling one step heating Wire liquid line solenoids as shown START UP Preliminary Checks 1 Compressor oil level must be visible at sight glass in each compressor crankcase Add oil if necessary 2 Each compressor must float freely on its mounting springs 3 All internal wiring connections must be tight and all barriers and covers must be in place Toggle switches for units 38AB054 064 and 084 must be in On position 4 Electrical power source must agree with unit nameplate rating 5 All service valves must be open 6 Fan cycling thermostat sensing bulb must be in air stream under fan no 1 7 Crankcase heater must be firmly locked into the compressor crankcase Leak Test the entire refrigerant system by the Pressure Method described in the Carrier Standard Service Techniques Manual Chapter 1 Section 1 6 Use R 22 at approximately 25 psig backed up with an inert gas to a total pressure not to exceed 245 psig Evacuate and Dehydrate the entire refrigerant system by either of the methods described in the Carrier Standard Service Techniques Manual Chapter 1 Section 1 7 f l Ioe e l fa MH 3 40 LLS SSS Sa aes See SS Bay 7h TWO STEP COOLING 38AB054 064 AND 084 LEGEND TC
5. COND COIL Plate Fins 3 rowt Sections 2 2 2 Face sq ft 35 4 39 0 49 6 60 4 78 0 99 2 120 8 Capacity lb 70 77 99 16 154 198 322 ELEC CONTROLS Time Guard Circuit Pressurestat Dual Cutout 375 Psig High Cut in 275 Psig L Cutout 29 Psig 29 Psig 29 Psig W Cut in E 44 Psig 45 Psig 63 Psig Pressurestat Capacity Control Cutout _ 57 Psig 57 Psig Cut in 87 Psig 87 Psig Pressurestat Oil Pressure Control Cutout 5 Psi Above Suction Pressure Thermostat Fan Cycling No 1 Opens 70 F Closes 75 F No 2 Opens 57 F Closes 62 F Discharge Line There stat Opens 290 F Closes 210 F PRESS RELIEF Fusible Plug CHECK VALVE Approximate charge for maximum system capacity Holding charge factory supplied with all units Unit 38AD044 and 38AB084 have 4 row coil Time Guard Circuits BASIC FUNCTIONS OF TIME GUARD CIRCUIT on all units provide for normal 12 to 15 sec momentary delays after the thermostat closes and before compressor s start The circuit also pro vides for a longer delay 4 min 45 sec to 5 min 30 sec in the event of thermostat short cycling or momentary power failure Storage capacity at 120 F condensing temp with condenser 80 full of liquid Short cycle protection 38AD024 THRU 044 UNITS In addition to the basic functions timers in these units provide additional delays for oil pressure switch bypass 40 sec winter start provision 150 sec bypass of low pressure switch and part windin
6. by pushing reset button on oil failure safety switch es All other safety controls on each unit are automatic reset with restart accomplished through unit timers Oil Pressure Safety Control OPS for each com pressor will stop unit if oil pressure differential is not established or maintained at either compressor If OPS stops unit determine and correct the cause such as loss of compressor oil or flooded compressor before restarting unit Failure to do so will constitute abuse Equipment failure due to abuse is not covered by the Warranty To restart unit push manual reset button in unit control box except 38AB054 and 064 units Reset button is on OPS on 38AB054 and 064 Compressor Motor Protection on 38AD024 thru _ 044 and 38AB084 consists of three temperature sensors one for each phase embedded in the motor windings and solid state modules in unit control box Sensors are part of a temperature bridge If a motor winding overheats the bridge circuit will unbalance and a silicone controlled rectifier in the module will de energize a relay which opens a set of normally open contacts in the module and stops the compressor If one sensor fails it can be jumped with a 75 ohm 2 watt resistor When checking or testing module do not apply more than 6 volts across sensor terminals Many test instruments exceed this voltage rating check before using If a component in a module fails on 38AD024 thru 044 the entire mod
7. 230 volt only have two power connections Maximum wire size is 350 MCM each On 38AD024 thru 034 units power terminal block is in the control box Remove the outer panel and remove the no 10 screw on the door Swing open door remove screws on barrier panel and remove barrier panel On 38AB054 064 and 084 units remove two screws holding hinged sheet metal barrier and swing open barrier Condenser fans must rotate clockwise when viewed from above If necessary correct direction of fan rotation by interchanging any two power input wires at disconnect switch 772 _COMPRESSOR FAN FLA MAX FLA LRA 4 AMPS 150 125 60 50 200 175 90 70 200 200 90 80 Rees wihKONN zZ o A Zz nN 2 o w o RONNIRONNIAOUY 250 250 110 100 NWO Oo amp OO Oo 300 300 150 125 350 350 175 150_ 450 450 225 175 NWADIN WADA NWO Oo KRONNIRONNIZRONN NWADKIN WADIN WOO KOOBIROOAIROOD NOTES 1 Dual compressor units have a 4 to 12 second delay between first and second compressor start up Units are supplied with either across the line or part winding start depending on unit size and voltage Refer to Electrical Data table Where two LRA values are shown units are part winding start all others are across the line Units have factory installed circuit breakers and or pullout fuses that meet NEC requirements for branch circuit over current protection and in sight disconnect Consult loc
8. B 044 054 064 16 24 ive Only 044 units use one piece legs Fig 3 Legs and Gussets Compressor Mounting 38AD024 028 034 UNITS As shipped com pressor is held down by special self locking bolts and plain lockwashers After unit is installed remove the self locking bolts one at a time and reassemble with flanged washers and neoprene snubbers as shown in Fig 4 Special flanged wash ers and neoprene snubbers are shipped in a cloth bag tied to one of the compressor feet Tighten all four bolts Then loosen each until the flanged washer can be moved sidewise 38AD044 38AB054 064 AND 084 UNITS com pressors are mounted on a common support channel Remove the four shipping bolts from mounting channels prior to start up Fig 4 Compressor Mounting 38AD024 028 and 034 Fan Thermostat Route the thermostat control bulb and capillary located in compressor section thru grommeted hole in compressor section base pan Do not kink capillary Position bulb in inlet air stream and secure to inlet air flange adjacent to compressor section Use clamp and screw provided in parts package If accessory head pressure control damper section is used secure bulb to air inlet side of damper Use hole in damper frame Integrate Unit 38AB054 064 and 084 only Connect refrigerant piping between the two sec tions using materials furnished with unit Arrange discharge and liquid lines as shown in Fig
9. Carrier OEE APOE MER EEA Air Cooled Condensing Units Table 1 Dimensions 38AD 38AD 38AD mil 024 028 034 DIMENSIONS ft in Length A 13 0 Width B 3 113 4 10 Height w o Legs C 22 4 OG Leg Height D 1 0 or 2 0 1 6 or 2 2 Mtg Holes Corner Legs 1 geI 0 1 Da K 3 8 3 83 4 7 J 0 0 0 0 0 0 Middle Legs te 3 10 3 10 4 BY L 3 3 M 9 4 te tases tee Nite Go oe CONNECTIONS in Suction ODM 1 Liquid ODM a OPENINGS in Suction E 2 4 Liquid F Tee yli y r 3 Control 4 holes G Power H 32 Unit 38AB084 has two suction connections HINGED CONTROL 024 034 BOX DOOR REQUIRED OVERHEAD AIR SPACE 8 0 REMOVABLE TOP COVER 38AD024 028 034 REMOVABLE END PANELS HINGED ACCESS DOOR REQUIRED OVERHEAD CONTROL BOX AIR SPACE AIR FLOW M p E jH 8 0 eS GUSSET mm HINGED POWER j 4 O BOTH SIDES 38AD044 4 o BOTH SIDES END PANELS 38AD 044 38AB 054 12 10 6 0 38 11 4 10 6 0 3 2 2 4 3 1 3 1 l1 8 1 4 or 2 0 1 6 or 2 2 1 8 or 2 4 2 O 1 6 O 1 e6 0 1 5 7 3 8 4 7 5 9 PREJA 0 0 0 0 0 0 5 7 3 10 4 BY 5 104 3 a 9 4 8 103 5 34 9 5 2 4 2 1 4 5 2 5 2 2 4 3 1 1 5 3 3 2 3 BOTTOM PANEL REMOVABLE REAR AIR FLOW OPENING PANEL REQUIRED OVERHEAD AIR SPACE 8 0 E F REMOVABLE TOP COVER
10. Jumper removed only when separate 24 volt power sources are available for heating and cooling To control heating device and provide automatic indoor fan operation on heating Fig 12 Control Circuit Wiring with 24 Volt Accessories 38AD units only Preliminary Charge Refer to Carrier Standard Service Techniques Manual Chapter 1 Section 1 8 for charging methods and procedures mentioned below Charge system with approximately 25 1b of R 22 75 1b for 38AD044 38AB054 064 and 084 units by the Liquid Charging Method and Charging by Weight Procedure Energize the Branch Circuit set space thermostat above ambient Close field disconnect switch and turn on unit circuit breakers Be sure compressor crankcase heater s is operating Allow crankcase heater s to operate a minimum of 24 hours before starting unit To Start Unit set space thermostat below ambient to ensure circuit operation On 38AD044 and 38AB084 push control circuit reset button s After starting unit there will be a delay of about 15 seconds 12 seconds on 38AD044 and 38AB084 before first compressor starts Charging System 1 Block condenser coils to maintain 125 F con densing temp at 280 psig then add additional 772 charge to clear sight glass If long liquid lines or vertical lifts greater than 25 ft are used a liquid line sight glass should be installed at condensing unit and used for charging purposes 2 After sight glass has cleared
11. Thermostat Cooling Field Wiring Field Supplied CR Control Relay LLS Liquid Line Solenoid TB Terminal Board at unit Fig 10 Control Circuit Wiring with Line Voltage 115 208 or 230 volt Thermostat j 1 ost n5 208 o B mee OR 230V l i 3 f 4 1 l I CONTROLS THERMOSTAT HHO7ATO72 SUBBASE HH93AZ080 LEGEND AHA Adjustable Heat SR Solenoid Relay Anticipator TB Terminal Board CC Cooling Compensator TC Thermostat Cooling CR Control Relay TH Thermostat Heating ee E Ah ne Factory Wired Indoor Fan Relay Z E P IMS Indoor Motor Starter Fiela Wreg LLS Liquid Line Solenoid Terminal Board Conn R Relay Accessory at Unit SDR Solenoid Dropping Relay Field Supplied Fig 11 Control Circuit Wiring with 24 Volt Accessories 38AB Units Only 712 CONTROL POWER AT 38AD UNIT 11I5 1 60 VOLT I 4 I i TB2 W ON 38AD UNIT X Ye BLACK ACCESSORY RELAY PACKAGE baat ACCESSORY THERMOSTAT L2 LEGEND CR Control Relay HD Heating Device IFC Indoor Fan Contactor IFR Indoor Fan Relay LLS Liquid Line Solenoid R Heating Relay field supplied 24 volt sealed coil OVA maximum rating SDR Solenoid Dropping Relay TB Terminal Board TC Thermostat Cooling TH Thermostat Heating Factory Wiring Field Wiring
12. additional charge must be added per Table 8 to flood subcooler circuits in condensers After Charging the System allow unit to run for about 20 minutes Stop unit and check compressor oil level Add oil only if necessary to bring oil into view in sight glass If oil is added run unit for additional 10 minutes Stop unit and check oil level If level is again low add oil only after determining that piping system is designed for proper oil return and that the system is not leaking oil Check the operation of all safety controls Replace all service panels Be sure that control panel door is closed tightly Table 8 Charging Data R 22 REFRIG CHG Ib Sub cooler REFRIG STORAGE CAP lb t 38AD024 70 38AD028 77 38AD034 99 38AD044 38AB054 38AB064 38AB084 161 For maximum system capacity without receiver At 120 F condensing temp with condenser 80 full of liquid NOTE Values shown do not include charging requirements for cooling coils and piping SERVICE Capacity Control is by either one or two suction pressure actuated unloaders Each controls two cylinders Unloaders are factory set see Table 9 but may be field adjusted No 1 unloader is on cylinder bank on same side of compressor as terminal box CONTROL SET POINT cylinder load point is adjustable from O to 85 psig To adjust turn control set point adjustment nut Fig 13 clock wise to its bottom stop In this position set
13. al codes Maximum fncremental Current Inrush during start up is LRA drawn by first winding of part winding start unit shaded area or across the line LRA of largest compressor when part winding start is not available Fans no 1 and 4 have single phase speed control motors on 208 and 230 volt units Units 38AB054 and 064 which have two contactors can be converted to part winding start by addition of two time delay relays Carrier part no HN67SKO01 for 208 and 230 volt units or no HN67SKO02 for 460 and 575 voit units Two additional contactors are also required with 460 and 575 volt units to be wired same as other part wind compressors Affix crankcase heater decal to unit disconnect switch Control Circuit Wiring Internal control voltage on 38AD units is 115 volts Internal control voltage on 208 and 230 volt 38AB units is the same as unit voltage On 460 and 575 volt 38AB units it is 115 volts All control circuit wiring must comply with applicable local and national codes Remote control wiring must enter unit control box thru control opening G on Fig 1 and connect to terminal block inside the control box Table 7 Maximum Field Wire Sizes 14 AWG to 2 0 ee Seay gt aeneon aa CT Compression Terminal attached to terminal block TB Terminal Block with integral compression terminal LINE VOLTAGE REMOTE CONTROL Install field supplied line voltage thermostat s as shown in Fig 10 for two step cooling
14. any side except compressor end may be installed against a wall if high leg setting is used and other three sides are unrestricted Place 38AB and 38AD units on high leg setting if accessory damper is used Erect Uniemsism legs and gussets attached to unit base skid s or frame Adjust all corner legs to desired height before attaching to unit 38AD024 028 034 AND 044 UNITS Block up or suspend unit With field supplied bolts bolt corner leg and angle gusset to each corner of unit Bolt two center legs to bottom of unit where compressor and coil sections meet Lower unit 38AB054 064 AND 084 UNIT Block up or suspend compressor with coil section Bolt corner leg and angle gusset to each corner at coil end Bolt two center legs to compressor end Allow one set of holes to project out past compressor section Bolt two center legs to bottom of unit where compressor and coil sections meet Lower unit Block up or suspend coil only section Bolt two corner legs and angle gussets to coil return bend end Butt coil only section against com pressor compartment allowing coil to rest on leg projections Remove top cover on compressor compartment and bolt sections together at legs and sides Table 3 Legs and Gussets Provided QUANTITY Parts packages in units Contain all mounting fasteners required for attaching legs and gussets CORNER LEG CENTER LEG gt ANGLE GUSSET 38AD 38AB 38A 38A
15. e thermo stat to serve the one liquid line feeding the two TXV s The third solenoid operates independently for the other step of cooling Suction Piping at Evaporator and TXV Bulb Location The purpose of these recommendations is to achieve good mixing of the refrigerant leaving the evaporator suction header for proper sensing by the TXV bulb 1 A minimum of two 90 elbows must be installed upstream of the expansion valve bulb location 2 The thermal bulb must be strapped to a vertical riser following the second elbow of item 1 This riser must be at least 15 pipe diameters high and the bulb should be fastened 10 pipe diameters above the preceding elbow 3 Size the suction line from near evaporator thru the 15 diameter long riser for high velocity Enter the suction pipe sizing charts in Carrier System Design Manual at corrected design tons each evaporator split and 80 feet equivalent length for 2 loss Choose the smaller size pipe when reading falls between two sizes on chart Since the selection of suction piping recommended for high velocity is approxi mately 20ft equivalent length this sizing method will result in about 0 5 friction loss for that section If a 2 loss is allowed for the entire suction line this leaves 1 5 for the balance of suction line and should be sized on that basis This high velocity sizing should be adequate for oil return up the 15 diameter long riser It should be checked If an
16. g 8D EVAPORATOR PIPING FREE DRAINING COIL SUCTION LINE 704 COMPRESSOR J ja rss A REFRIGERANT PIPING Refrigerant Line Sizes will depend on length of piping required between condensing unit and evap orator Consideration must be given to liquid lift and to compressor oil return Refer to Part 3 of Carrier System Design Manual for line sizing information and Fig 8 for recommended piping details Single Pumpout Control All units are factory wired to operate on single pumpout control and require a field supplied liquid line solenoid valve sized for minimum pressure drop to be installed immediately ahead of each expansion valve If unit is to be used with a chiller wiring modifications may be necessary Refer to 38AB Application Data Chilled Water Applications Refrigerant Drier and Moisture Indicator A filter drier s and a liquid moisture indicator are shipped with unit for field installation Refer to Fig 9 for typical recommended piping arrange ments and to Table 5 for physical data on driers Receiver No receiver is provided with unit It is recommended that one not be used Piping Procedure Do not remove plastic dust plugs from suction and liquid line stubs in com pressor compartment until piping connections are ready to be made Pass nitrogen or other inert gas thru piping while brazing to prevent formation of copper oxide REDUCING COUPLING REDUCING ELBOW
17. g start 1 sec if used 712 38AB084 UNIT Timers in this unit provide basic function plus 40 sec bypass for oil failure switch and 1 sec delay to accomplish part winding start For specific sequence for each unit refer to Timing Charts in Fig 14 CONTROL SET POINT ADJUSTMENT NUT POWER HEAD PRESSURE DIFFERENTIAL ADJUSTMENT SCREW PISTON DIFFERENTIAL SCREW SEALING CAP wee a ee CAP MUST BE REPLA CED TO PREVENT REFRIGERANT LEAKAGE Fig 13 Capacity Control Valve 9 S aA Z O pe eo _ 150 SEC 5 1 AA2 12 SEC 2 He 2 6 SEC BBI CE en ee ee s SEC 705 EE fs 5 SEC 22 j 40 SEC 25 DD2 2 6 SEC 25 N ah 150 SEC 55 MIN v 38AD024 THRU 044 UNITS be 0 4 45 SEC ah S SEC EES 38AB054 THRU 064 UNITS 60 SEC I2 SEC 2 e ie E Gee 1SEC 205 ig H 5 SEC 2 Jeer f ae eee NOTE BLACK INDICATES CLOSED CONTACTS 38AB084 UNITS Fig 14 Timing Charts Control Circuit Reset 38AD024 THRU 044 AND 38AB084 Control circuit locks out on these units in the event of oil pressure loss excessive motor temperatures or excessive discharge temperatures Reset is accomplished by pushing reset button s in unit control box 38AB054 AND 064 Loss of oil pressure or excessive motor temperatures cause control circuit lock out on these units Reset is accomplished
18. h the two latches on the outer hinged door and swing open outer door Remove screws on barrier panel and remove barrier to expose wiring gt Table 6 Electrical Data 3 Phase 60 Hz UNIT Nameplate Supplied Moda Voltage Voltage MWA 400 200 180 229 38AD 500 230 207 264 024 600 460 414 528 100 575 518 660 180 229 207 264 414 528 518 660 38AD 028 180 229 38AD 207 264 034 414 528 518 660 See 400 200 180 229 38AD 500 230 207 264 044 600 460 414 528 100 575 518 660 _ 410 187 229 38AB 510 198 254 054 610 414 506 110 518 632 410 187 229 38AB 510 198 254 064 610 414 506 110 518 632 410 187 229 246 206t 38AB 510 198 254 226 190t 084 610 414 506 189 110 518 632 152 Shaded values are LRA drawn by first winding of part winding start units not standard on 38AB054 064 but may be field modified See Note 1 Larger value is total LRA FLA Full Load Amps ICF Maximum Instantaneous Current Flow sum of LRA of last compressor to start and FLA of all other motors in unit and contro circuit current LRA Locked Rotor Amps MWA Minimum Wire Amps per NEC Section 430 24 Values based on maximum of 1 voltage drop in line Units are suitable for use on electrical systems where voltage supplied to the unit terminals is never below or above the listed limits Units 38AB084 208
19. lose discharge shutoff valve 2 Relieve crankcase pressure by disconnecting line at compressor which goes to low pressure connection of oil safety switch 3 Add oil thru oil filter connection 4 Remove oil thru drain plug in bottom cover Remove small amounts of oil thru oil discharge connection with compressor running Fig 16 Fan Adjustment 11 For replacement items use Carrier Specified Parts Manufacturer reserves the right to change any product specifications without notice CARRIER AIR CONDITIONING COMPANY SYRACUSE Tab 4 Form 38AD 6S Supersedes 38AD 5S Printed in U S A 373 4 72 Codes B and MS NEW YORK Catalog No 533 860 a fc ON
20. oil return connection at the bottom of the suction header is supplied with an evaporator this connection must be teed in ahead of first mixing elbow Fig 8 When the compressor is below the evaporator the riser at the evaporator does not have to extend as high as the top level After the 15 diameter riser has been provided the suction may elbow down immediately Safety Relief A fusible plug is located on unit liquid line before liquid valve WIRING AND ELECTRICAL DATA Power Supply Electrical characteristics of avail able power supply must agree with unit nameplate rating Supply voltage must be within tolerances shown in Table 6 Phase unbalance must not exceed 2 Operation of unit on improper supply voltage or with excessive phase unbalance con stitutes abuse and is not covered by Carrier Warranty Power Wiring All power wiring must comply with applicable local and national codes Install a field supplied branch circuit disconnect switch of a type that can be locked Off or Open Run power wires from the disconnect switch thru the power opening H on Fig 1 on unit and connect to terminal block just inside the opening On 38AB084 there are two terminal blocks on 208 volt and 230 volt units only Each is limited to 350MCM maximum wire size see Table 7 These units are provided with two power openings to accommodate two conduit runs For access to power opening and terminal blocks on 38AD044 unlatc
21. point is 85 psig Then turn adjustment counterclockwise to desired control set point Every full turn counterclockwise decreases set point by 7 5 psig PRESSURE DIFFERENTIAL difference between cylinder load and unload points is adjustable from 6 to 22 psig To adjust turn pressure differential adjustment screw Fig 13 counterclockwise to its back stop position In this position differential is 6 psig Then turn adjustment clockwise to desired pressure differential Every full turn clockwise increases differential by 1 5 psig Table 9 Physical Data UNIT 38AD024 38AD028 WADO 38AD044 38AB054 38AB064 38AB084 OPER WT Ib d 1750 1900 2300 3200 3145 3830 4960 REFRIGERANT Oper Chg Ib 28 O 66 0 ie 57 0 d 132 0 COMPRESSOR Reciprocating Hermetic 1750 rpm Number Model 06ED250 06EE266 06EE275 OSEA Jore Cylinders 4 l 4 6 Oil pt 14 14 19 Crankcase Htr 125 Watts Protection Solid State amp Ckt Bkr Thermotector amp Ckt Bkr er Cap Control Suction Pressure Cylinder Unloader s No 1 Unloader Settings psig Load 76 78 78 88 79 79 79 Unload 58 60 60 66 66 66 66 No 2 Unloader Settings psig Load 76 76 76 76 76 Unload 58 58 58 58 58 COND FANS Axial Flow Direct Drive Number 3 3 3 3 6 6 6 Rpm 1140 1140 1140 1140 1140 1140 1140 Diam in 26 30 30 30 30 30 30 Motor Hp ea 1 E Cfm 18 200 25 200 28 200 31 000 50 400 56 400 62 000
22. rmo stat capillary passing thru lower part of evaporator coil and with remainder of capillary inserted between fins on entering air side of coil Connect thermostat electrical contacts into indoor cooling thermostat circuit or in series with compressor holding coil Thermostat is set to cut out at 25 F and cut in at 55 F Contact rating is 16 amps and 230 volts As evaporator coil frosts coil fin temperature drops to thermostat cutout setting and stops compressor Evaporator fans keep running to defrost coil with room air As indoor coil defrosts fin temperature will rise to thermostat cut in setting Compressor starts when cooling is required NOTE Use a defrost thermostat on all systems operating with outdoor temperatures below 45 F Fan Adjustment When replacing a fan adjust fan until top surface of hub plate is below the top of the orifice ring as indicated in Fig 16 Then tighten both setscrews located over the keyway of the fan hub of the motor shaft Seal recessed area of fan hub bore with Permagum to prevent rusting Lubrication FAN MOTORS have permanently lubricated bear ings No provisions for lubrication are made COMPRESSOR has its own oil supply Loss of oil due to a leak in the system should be the only reason for adding oil after the system has been in operation To Add or Remove Compressor Oil 1 Stop compressor and close suction service valve Pump down compressor to 2 psig Stop com pressor and c
23. ule must be replaced On 38AB084 the transformer is external to the module and may be replaced separately Replace transformer with a Carrier specified balanced transformer To restart compressor after shutdown due to motor protection trip push control circuit reset button in unit control box Safety Relief Ali 38AB AD units are protected against excessive pressure by a fusible plug inserted in the liquid line Winter Start Control On 38AB units not necessary on 38AD units because the timer supplies this function install a liquid line pressure stat Carrier part no HKO2ABO026 and evaporator freeze up protector defrost thermostat Carrier part no HH22UA025 38AD control circuits incorporate a 150 sec onds timed bypass of the low pressure switch to allow unit to start under low ambient conditions An evaporator freezestat must also be installed in series with the control thermostat s to prevent coil freeze up See lower part of Fig 15 EDT Wiring section LIQUID LINE PRESSURESTAT Connect to system liquid line service valve port Connect switch into control circuit as shown on unit label diagram or in Fig 15 Pressurestat is set to cutout at 5 psig with a differential of 10 psig Do not change setting Fig 15 if Unit Wiring Changes for Winter Start Control DEFROST THERMOSTAT Position switch so that moisture cannot enter switch insulator Install control with approximately 2 in of top of the
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