TM 9-4120-357-14
TABLE 5-1.
TROUBLESHOOTING (Cont)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 6.
Disconnect time delay relay, K6. Apply 24-26 volts dc to terminals 1-5, and check to see that continuity
exists in terminals 2-3 within 19 to 31 seconds.
Replace defective time delay relay, K6.
Step 7.
Disconnect plug, P11, from compressor receptacle. Using an ohmmeter on continuity tester, test recep-
tacle points D-E, D-F and E-F. Continuity should be indicated. Test points D, E and F to compressor
casing or common ground. No continuity should be indicated. Replace compressor that does not meet
continuity requirements.
2.
COMPRESSOR STARTS BUT STOPS AT ONCE - "SHORT CYCLES".
Step 1.
Check sight-glass liquid indicator for bubbles while compressor is operating. If bubbles appear, check
refrigeration system for leaks.
Repair leaks, and add refrigerant until sight-glass is clear when compressor is running.
Step 2.
Connect pressure gauges to suction and discharge service valves. Check system pressures as follows:
If pressures are too low, check for leaks and add refrigerant; if too high, bleed off refrigerant until
pressure is normal.
Step 3.
If pressures are normal, turn off power, and short-circuit high or low pressure cutoff switch. Turn on
power for maximum of 12 seconds, and see whether compressor operates normally.
CAUTION
Do not exceed 12 second operating time or vacuum may be formed in
suction side of refrigeration system and damage compressor.
Bleed off refrigerant over a period of 5 to 6 hours to prevent oil being blown out of system, then re-
place faulty pressure cutout switch and recharge system.
NOTE
Use the Pressure-Temperature Relationship Table that follows.
5-3
