TM 9-4120-378-14
Table 4-2. Unit Troubleshooting - Continued
Malfunction
Test or Inspection
Corrective Action
AIR CONDITIONER FAILS TO OPERATE - Continued
1.
Inspect main power receptacle connections for breaks.
Step 3.
Replace connector. (Refer to paragraph 4.28.)
Step 4.
Check for loose electrical connections.
Tighten connections.
Inspect rotary selector switch for incorrect setting. (See Table 2-2., Operator
Step 5.
Control Setting,)
Turn selector switch to COOL or VENTILATE.
Check to see whether Control or COMPRESSOR CIRCUIT BREAKER is in the
Step 6.
OFF position or is defective.
a. Make continuity check with ohmmeter.
b. Reset circuit breaker.
Disconnect control circuit transformer and make continuity check of primary and
Step 7.
secondary windings, and from windings-to-case, using ohmmeter. Reset circuit
breaker.
If windings do not show continuity or if windings-to-case continuity exists, replace
transformer. (Refer to paragraph 4.31.)
Apply 30-volt AC to input side terminals of control circuit rectifier, and check to see
Step 8.
that 24-28 volts DC exists at end terminals.
Replace bad rectifier. (Refer to paragraph 4.30.)
INSUFFICIENT COOLING
2.
Step 1.
Check to see that Mode Selector switch is properly positioned.
Step 2.
Check liquid sight indicator level to see that refrigerant is colorless and clear.
Yellow indicates moisture in system. Milky or bubbly refrigerant indicates low level
refrigerant charge.
Report condition to Direct Support Maintenance personnel.
Step 3.
Inspect condenser coil for dirt.
Clean coil with 25-30 psi (1 .76-2 .11 kg/cm2) compressed air.
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