TM 9-4120-357-14
TABLE 5-1.
TROUBLESHOOTING
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
WARNING
Hearing protection must be worn when maintenance is performed while air
conditioner is in operation. Failure to heed this Warning can result in
hearing loss or injury. Disconnect power from the air conditioner before
performing maintenance on the electrical system. The voltage used can
be lethal. Avoid contact with liquid refrigerant or escaping refrigerant gas.
Irreversible tissue damage can occur from sudden freezing.
1.
COMPRESSOR WILL NOT START.
Step 1.
Check continuity of circuit breaker. Unscrew four panel fastener screws, and remove front panel from air
conditioner. Unscrew four panel fastener screws, and remove junction box cover. Tag and disconnect
leads from circuit breaker, and check continuity of each pair of terminals, using an ohmmeter or continu-
ity tester.
Replace circuit breaker if bad.
Step 2.
NOTE
If a fuse indicates no continuity it may have blown because of a
short circuit or overload in the transformer or one of the other com-
ponents.
Using an ohmmeter or continuity tester, remove fuses from fuse blocks and check conti-
nuity. Replace fuses that show no continuity, and proceed to Step 3.
Step 3.
continuity. Replace transformer if continuity requirements are not met.
Step 4.
Disconnect leads of rectifier-filter. Apply 28-30 volts ac to leads 1-4, and check leads 2-3 for 24-28 volt
dc output.
Replace bad rectifier-filter.
Step 5.
Disconnect compressor relay, K9. Apply 24-28 volts dc to terminals A1-A2, B1-B2, C1-C2. All should
indicate continuity.
5-2