Carrier 38AH044 38AH044-134 Specifications download pdf (Page 39)

START-UP

Compressor crankcase heaters must be on for 24 hours be-

fore start-up. To energize the crankcase heaters, set the space

thermostat above the ambient so there will be no demand for

cooling. Close the field disconnect and turn on the fan circuit

breakers. Leave the compressor circuit breakers off/open. The

crankcase heaters are now energized.

Sequence of Operation — Units are controlled with

electromechanical components. Each refrigeration circuit (ex-

cept 38AH044-084 optional single-circuit units) is operated by

an independent timer which controls the operation sequence of

each circuit.

On a call for cooling, first stage cooling thermostat TC1

closes. Condenser fans and timer (TM) are energized. After

approximately 7 seconds, timer contacts E-E1 close. Approxi-

mately 12 seconds after TC1 closes, normally open timer con-

tacts B-B1 close for 1 second. This energizes compressor A1

contacts CA1 and starts the compressor. At the same time, sole-

noid drop relays (SDRs) and liquid line solenoid valve no. 1

(LLS-A for 38AH044-084 dual-circuit units; LLS-A1 for all

other units) opens, and timer relay no. 1 (TR2) is energized.

Normally open TR2 contacts close, completing a circuit around

B-B1 and through compressor A1 contactors to maintain com-

pressor operation when B-B1 contacts open. Contacts E-E1

remain closed for approximately 40 seconds to bypass the oil

pressure switch (OPS). If oil pressure is insufficient when con-

tacts E-E1 open, the compressor stops, the timer cycles off, and

the control circuit locks out. At start-up, timer contacts D-D1

are closed, bypassing low-pressure relay contacts LPR-A for

minutes. This provides a winter start-up feature.

Approximately 2

minutes after TC1 closes, timer contacts

D-D1 open and D-D2 close. If pressure is insufficient to close

the low-pressure switch, the low-pressure switch relay is open,

the compressor shuts down, and the Time Guard control is ini-

tiated. (Time Guard control prevents compressor from restart-

ing for 5 minutes after the demand for cooling is satisfied.)

Unit Control Box — (See Fig. 33.) Viewed facing com-

pressors, the control box is at the left end of the unit. All in-

coming power enters through the control box. The control box

contains power components and electronic controls. Outer pan-

els are hinged and latched for easy opening. Remove screws to

remove inner panels. Outer panels can be held open for service

and inspection by using door retainer on each panel. Remove

bottom pin from door retainer assembly, swing retainer out

horizontally, and engage pin in one of the retainer ears and the

hinge assembly.

Condenser Fans — Each fan is supported by a formed

wire mount bolted to the fan deck and covered with a wire

guard. The exposed end of the fan motor shaft is protected

from weather by grease. If fan motor must be removed for ser-

vice or replacement, be sure to regrease fan shaft and reinstall

fan guard. For proper performance, fan should be

in.

(22 mm) below top of venturi on the fan deck to top of the fan

hub for 60-Hz units, and

in. (13 mm) for 50-Hz units. (See

Fig. 34.) Tighten setscrews to 15 ± 1 ft-lbs (20  1.3 N-m).

Figure 34 shows proper position of mounted fan.

CYLINDER

HEADS

OIL PRESSURE SWITCH AND

CAPACITY CONTROL

PRESSURE SWITCH CAPILLARIES

MUFFLER

HIGH-

PRESSURE

SWITCH

FAN CYCLING

PRESSURE SWITCH

LOW-

PRESSURE

SWITCH

SIGHT

GLASS

MOUNTING

SPRING

(HIDDEN)

RAIL

OIL

EQUALIZER

LINE

CRANKCASE

HEATER

SIGHT

GLASS

PRESSURE RELIEF

VALVE

NOTE: Units 38AH044-084 and 38AH124, 134 compressors are pan mounted. Units 38AH094 and 104 compressors are mounted on rails.

Fig. 32 — 06E Compressors, Typical

IMPORTANT: Check for proper fan rotation (clockwise

viewed from above). If necessary, switch leads to

reverse.

1 2 ... 34 35 36 37 38 39 40 41 42 43 44 ... 55 56

Comments to this Manuals

No comments

Carrier 38AH044 38AH044-134 Specifications Page 39

Comments to this Manuals

Related products and manuals for Air compressors Carrier 38AH044 38AH044-134