TM 9-4120-378-14
5.2 DIRECT SUPPORT TROUBLESHOOTING. See table 5-1.
Malfunction
Test or Inspection
Corrective Action
COMPRESSOR WILL NOT START
1.
Make continuity check of control circuit. See Appendix F for control circuit
Step 1.
schematic and wiring diagram. (Refer to paragraph 4.24.)
a. Repair loose or broken connections.
b. Replace bad components. (Refer to paragraphs 4.24, 4.25 and 4.26.)
Make continuity check of circuit breaker. (Refer to paragraph 4.24.)
Step 2.
Replace bad circuit breaker. (Refer to paragraph 4.24.)
Test starting relay or start capacitor. (Refer to paragraphs 4.27 and 4.29.)
Step 3.
Step 4.
Check continuity or compressor motor leads, and leads to casing using ohmmeter.
(Refer to paragraph 5.27.)
Replace bad compressor. (Refer to paragraph 5.27.)
Check continuity of HIGH and LOW pressure switches at room temperature.
Step 5.
Continuity should exist. (Refer to paragraph 5.21.)
a. If continuity does not exist. press reset button and recheck.
b. Replace faulty HIGH or LOW pressure switch. (Refer to paragraph 5.21.)
Check polarity of power input plug (P1 ) using voltmeter. With positive (+) lead in
Step 6.
pin A and negative (-) lead in pin B, voltage should be115 Vac. With positive (+)
lead pin A and negative (-) lead in pin D, voltage should be 115 Vat. With positive
(+) lead in pin B and negative (-) lead in pin D, voltage should be zero volts.
Replace power input plug (P1 ) which does not pass above test.
2.
COMPRESSOR STARTS, BUT STOPS AT ONCE - "SHORT CYCLES"
Test compressor run capacitor. (Refer to paragraph 4.29.)
Step 1.
Replace bad compressor run capacitor. (Refer to paragraph 4.29.)
Inspect evaporator coil for dirt or icing, and check for obstructions at outlet louver.
Step 2.
(Refer to paragraphs 4.18 and 4.37.)
a. Clean dirty evaporator coil.
b. Defrost in HEAT mode, or remove obstructions from outlet louver.
