Carrier 38AH044 38AH044-134 Specifications download pdf (Page 41)

NOTE: Use only Carrier approved compressor oil. Approved

sources are:

Totaline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

Witco Suniso . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3GS

Shrieve Chemical . . . . . . . . . . . . . . . . . . . . . . . . . . . Zerol 150*

Texaco Ind. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WFI-32-150

IGI Petroleum Ind. . . . . . . . . . . . . . . . . . . . . . . . . . . .Cryol-150

*Alkyl Benzene Oil.

Do not reuse oil that has been drained out, or oil that has

been exposed to atmosphere.

REMOVE OIL — Pump down compressor to 2 psig

(14 kPa). Loosen the

-in. (6.4-mm) pipe plug at the compres-

sor base and allow the oil to seep out past the threads of the

plug.

NOTE: The crankcase will be slightly pressurized. Do not

remove the plug, or the entire oil charge will be lost.

Small amounts of oil can be removed through the oil pump

discharge connection while the compressor is running.

Preliminary Charge — Refer to GTAC II (General

Training Air Conditioning), Module 5, Charging, Recovery,

Recycling, and Reclamation for charging procedures. Using

the liquid charging method and charging by weight procedure,

charge each circuit with the amount of R-22 listed in Table 3A,

3B, 4A, or 4B.

Start Unit — The field disconnect is closed, the fan circuit

breaker is closed, and the space thermostats are set above ambi-

ent so that there is no demand for cooling. Only the crankcase

heaters are energized.

Close the compressor circuit breakers and then reset both

space thermostats below ambient so that a call for stage one

cooling is ensured. Lead refrigeration circuit thermostat TC1

must be set to call for cooling at a lower temperature than lag

refrigeration circuit thermostat TC2. See Table 16 for lead/lag

circuits on all units. Now set TC2 for cooling.

NOTE: Do not use circuit breakers to start and stop the com-

pressor except in an emergency.

38AH044-084 DUAL-CIRCUIT UNITS — Start-up of lead

compressor A1 (Table 16) will be delayed from 12 seconds to

minutes from the time the call for cooling is initiated by

TC1. After the lead compressor starts, close the TC2 thermo-

stat to start lag circuit compressor B1. Compressor B1 will start

a minimum of 60 seconds after thermostat TC2 is closed.

38AH044-084 OPTIONAL SINGLE CIRCUIT UNITS —

Start-up of lead compressor A1 (Table 16) is delayed from

12 seconds to 5

minutes from the time the call for cooling is

initiated by TC1. Closure of TC2 will actuate LLS-A2. Lag

compressor A2 is controlled by D-D2 timer contacts and ca-

pacity control pressure switches (CCPSs) which monitor com-

pressor suction pressure. The lag compressor starts approxi-

mately 2 minutes after the lead compressor starts if the suction

pressure is above the CCPS set point.

38AH094,104 UNITS — Start-up of lead circuit A, compres-

sor A1 (Table 16) is delayed from 12 seconds to 5

minutes

from the time the call for cooling is initiated. After lead circuit

A, compressor A1 starts, close refrigeration circuit thermostat

TC2 to start lag circuit B, lead compressor B1. Start-up of com-

pressor B1 is delayed from 12 seconds to 5

minutes. (Circuit

B of unit 38AH094 has only one compressor.)

Each circuit’s lead compressor start-up is controlled by the

unit control timer. The circuit’s lag compressor start-up is con-

trolled by the D-D2 timer contacts and capacity control pres-

sure switches (CCPSs) which monitor compressor suction

pressure. The circuit’s lag compressor will start approximately

minutes after a call for cooling if compressor pressure is

above CCPS set point.

38AH124,134 UNITS — Start-up of the lead circuit (module

124A or 134A) lead compressor A1 (Table 16) is delayed from

12 seconds to 5

minutes from the time the call for cooling is

initiated by TC1. Lag compressor A2 is controlled by D-D2

timer contacts and capacity control pressure switches (CCPSs)

which monitor compressor suction pressure. The lag compres-

sor starts approximately 2

minutes after the lead compressor

starts if the suction pressure is above the CCPS set point.

After the lead circuit (module 124A or 134A) lead compres-

sor A1 (Table 16) starts, close the TC2 thermostat to start the

lag circuit (module 124B or 134B) lead compressor (A1). Lag

circuit compressor A1 start-up is delayed from 12 seconds to

minutes from the time the call for cooling is initiated by

TC2. Lag compressor A2 is controlled by D-D2 timer contacts

and CCPSs which monitor compressor suction pressure. Lag

compressor A2 starts approximately 2

minutes after lead

compressor A1 starts if the suction pressure is above the CCPS

set point.

Adjust Refrigerant Charge

With all fans operating, and all compressors on the circuit

being serviced operating at full capacity, adjust the refrigerant

charge in accordance with the unit charging charts located on

the inside of the control box doors and in Fig. 35-48. Charge

vapor into compressor low-side service port located above oil

pump crankshaft housing. Measure pressure at the liquid line

service valve, making sure a Schrader depressor is used if re-

quired. Also, measure liquid line temperature as close to the

liquid service valve as possible. Add charge until the pressure

and temperature conditions of the charging chart curve are met.

If liquid pressure and temperature point fall above curve, add

charge. If liquid pressure and temperature point fall below

curve, reduce the charge until the conditions match the curve.

If the sight glass at location A (Fig. 13 and 14) is cloudy,

check refrigerant charge again. Ensure all fans and compres-

sors on the circuit being serviced are operating. Also ensure

maximum allowable liquid lift has not been exceeded.

If the sight glass at location A is clear and the sight glass at

location B is cloudy, a restriction exists in the line between the

2 sight glasses. Check for a plugged filter drier or partially

open solenoid valve. Replace or repair, as needed.

CAUTION

Never charge liquid into the low-pressure side of system.

Do not overcharge. During charging or removal of refriger-

ant, be sure indoor-fan system is operating. Failure to com-

ply could result in equipment damage.

CAUTION

Never charge liquid into the low-pressure side of system.

Do not overcharge. During charging or removal of refriger-

ant, be sure indoor-fan system is operating. Failure to com-

ply could result in equipment damage.

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Carrier 38AH044 38AH044-134 Specifications Page 41

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