Section III. REMOVAL AND INSTALLATION OF MAJOR COMPONENT'S OR AUXILIARIES

TM 5-4120-274-15

5-14. High Crankcase Temperature

5-10. Compressor Noisy

Possible remedy

Probable cause

Probable cause Possible remedy

Excessive superheat-------- Reset expansion valve (para

Insufficient clearance Replace compressor (para

6-12c).

between rotating 5-17).

compressor parts

5-15. Little or no Heating Capacity

Bearings worn---------- Replace compressor (para

5-17).

Wiring and wiring harness Replace wire or wiring

Slugging due to floodback

Check setting or expansion

harness (para 5-22)

defective

valve. Check sensing bulb.

of refrigerant

5-16. System Losing Cooling Capacity

5-11). Hissing

If the system is losing cooling capacity, or is in

Possible remedy

Probable cause

some way not functioning properly, a check of

Add refrigerantt (para 5-

Insufficient refrigerant

system operating pressure will frequently lead to

21e).

flow through expansion

cause of malfunction. Install pressure gages on

valves

access fittings of suction and discharge lines and

expose gages to system pressure. Compare gage

5-12. Cold Compressor

readings with normal ranges of systems pressures

Possible remedy

Probable cause

listed in table 5-1

Liquid carrying over from Check refrigerant charge

Table 5-1. Normal Operating Pressures

evporator or through

and expansion valves.

(para 3-51).

quench valve

5-13. Cylinders and Crankcase Sweating

Possible remedy

Probable cause

Floodback------ Check refrigerant charge and

expansion valves. (para 3-

51).

Section III. REMOVAL AND INSTALLATION OF MAJOR COMPONENT'S

OR AUXILIARIES

b. Removal.

5-17. Compressor

a. General. The sole purpose of the compres-

(1) Remove front access panel, refer to para-

sor is to raise the pressure of refrigerant gas from

graph 3-18 and pullout the junction and control

evaporator pressure to condensing pressure. The

box, refer to paragraph 3-28.

function of the compressor is to deliver refriger-

(2) Discharge refrigerant from system refer

ant to the condenser at a pressure and tempera-

to paragraph 5-21b.

ture at which the condensing process can readily

be accomplished. The motor/compressor is a her-

(3) Remove condenser coil, refer to para-

metically sealed unit and is not repairable in the

graph 6-5.

field. An inoperative compressor is usually due to

a mechanical failure causing the compressor to

(4) Refer to figure 3-6 and remove compres-

freeze, control failure, or a motor burnout. If

sor through rear of unit.

the motor/compressor is mechanically frozen or

c. Installation.

there has been a motor burnout, the compressor

must be removed and replaced. When the motor

(1) Refer to figure 3-6 and install compres-

of a hermetic compressor fails, high temperatures

sor.

may develop within the compressor causing a

breakdown of the oil and refrigerant, resulting

(2) Refer to paragraph 6-5 and install the

in formation of acid, moisture, and sludge. All

condenser coil.

these are extremely corrosive and must be flushed

(3) Evacuate and recharge the unit, refer to

from the system. Repeated burnouts will occur if

paragraph 5-21.

all of the contaminants are not removed.

5-2