Chapter 5: GENERAL MAINTENANCE INSTRUCTIONS

5-4120-273-15

CHAPTER 5

GENERAL MAINTENANCE INSTRUCTIONS

Section I. SPECIAL TOOLS AND EQUIPMENT

5-2. Specially Designed Tools and Equipment

5-1. Special Tools and Equipment

No specially designed tools or equipment are re-

No special tools or equipment are required to per-

quired to perform field and depot maintenance on

form field and depot maintenance on the air con-

the air conditioners.

ditioners.

Section Il. TROUBLESHOOTING

Possible remedy

Probable cause

5-3. General

Check and clean tubing.

Dirt or restriction in

This section provides information useful in diag-

tubing to pressure

nosing and correcting unsatisfactory operation or

switch

Faulty pressure switch -----Repair or replace pressure

failure of the air conditioner or any of its compo-

switch (para 6-6 or 6-7).

nents. Each trouble symptom stated is followed by

Condenser capacity reduced Remove excess refrigerant

a list of probable causes. The possible remedy

(para 5-21b).

by refrigerant over-

recommended is described opposite the probable

charge accompanied by

cause.

high discharge pressure

Air in system ----------------Evacuate system (para

5-21c .

5-4. Compressor Will Not Start

Possible remedy

Probable cause

5-6. High Discharge Pressure

Power off -------------Check relays (para 3-37)

Possible remedy

Probable cause

fuses (para 3-33) and

Condenser fan inoperative --Check condenser fan motor

wiring, (para 5-22) and

(para 3-24).

circuit breaker. (para

Too much refrigerant -----Remove excess refrigerant

3-35).

(para 5-21b).

Thermostat set too high ----Adjust thermostat (fig. 2-2).

Air in system ------- Evacuate system (para

Loose electrical connections Tighten connections. Check

5-21c).

or faulty wiring

wiring and rewire if

necessary (para 5-22).

Compressor motor burned Check and replace compres-

5-7. Low Discharge Pressure

out

sor (para 5-17) if

Possible remedy

Probable cause

defective.

Clean the Line.

Suction line paritally

Replace high-low pressure

High-low pressure switch

obstructed

switch (para 6-6 and

defective

6-7) .

5-8. Flooding

Thermostat defective -----------Replace thermostat (para

3-31).

Possible remedy

Probable cause

Defective or improperly

Reset expansion valve

5-5. Compressor Cycles Intermittently

(para 6-12c).

set expansion valve

Possible remedy

Probable cause

5-9. Low Suction Pressure

Low pressure switch

Check tubing to switch, may

Possible remedy

Probable cause

erratic in operation

be clogged. Also check

setting of switch. It may

Add refrigerant (pare

Insufficient refrigerant

be too high.

in system

5-21d) .

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

Add refrigerant (para

Insufficient refrigerant

(para 6-12c).

5-21d).

in system

5-1