Section III. REMOVAL AND INSTALLATION OF MAJOR COMPONENTS OR AUXILIARIES

TM 5-4120-273-15

5-14. High Crankcase Temperature

5-10. Compressor Noisy

Probable cause

Possible remedy

Possible remedy

Probable cause

Excessive superheat ---------Reset expansion valve

Replace compressor

Insufficient clearance

(para 6-12c).

(para 5-17).

between rotating com-

Liquid line filter clogged -----Replace filter (fig. 3-3).

pressor parts

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

5-15. Little or no Heating Capacity

5-17).

Probable cause

Possible remedy

Slugging due to floodback Check setting of expansion

Wiring and wiring harness Replace wire or wiring

valve. Check thermal

of refrigerant

harness (para 5-22).

defective

bulb.

5-16. System losing Cooling Capacity

5-11. Hissing

If the system is losing cooling capacity, or is in

Probable cause

Possible remedy

some way not functioning properly, a check of sys-

Insufficient refrigerant

Add refrigerant (para

tem operating pressure will frequently lead to

flow through expansion

5-21d).

cause of malfunction. Install pressure gages on

valves

access fittings of suction and discharge lines and

Clogged liquid line filter ----------Clean filter (pars 3-9b).

expose gages to system pressure. Compare gage

readings with normal ranges of systems pressures

5-12. Cold Compressor

listed in table 1.

Possible remedy

Probable cause

Table 5-1. Normal Operating Pressures.

Liquid carrying over from Check refrigerant charge

and expansion valves.

evaporator or through

(para 3-51).

quench valve

5-13. Cylinders and Crankcase Sweating

Probable cause

Possible remedy

Floodback ----------------Check refrigerant charge

and expansion valves.

(pars 3-51).

Section III. REMOVAL AND INSTALLATION OF

MAJOR COMPONENTS OR AUXILIARIES

the system. Repeated burnouts will occur if all of

5-17. Compressor

the contaminants are not removed.

a. General The sole purpose of the compres-

b. Removal.

sor is to raise the pressure of refrigerant gas from

evaporator pressure to condensing pressure. The

(1) Remove front access panel, reference

paragraph 3-18 and pullout the junction and con-

function of the compressor is to deliver refriger-

trol box, reference paragraph 3-28.

ant to the condenser at a pressure and tempera-

ture at which the condensing process can readily

(2) Discharge refrigerant from system ref-

erence paragraph 5-21b.

be accomplished. The motor/compressor is a her-

metically sealed unit and is not repairable in the

(3) Remove condenser coil, reference para-

field. An inoperative compressor is usually due to

graph 6-5.

a mechanical failure causing the compressor to

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

freeze, control failure, or a motor burnout. If the

sor through rear of unit.

motor/compressor is mechanically frozen or there

c. Installation.

has been a motor burnout, the compressor must

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

be removed and replaced. When the motor of a

pressor.

hermetic compressor fails, high temperatures may

develop within the compressor causing a break-

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

down of the oil and refrigerant, resulting in for-

condenser coil.

mation of acid, moisture, and sludge. All these

(3) Evacuate and recharge the unit, refer-

are extremely corrosive and must be flushed from

ence paragraph 5-21.

5-2