TM 9-4120-371-14
Table 4-2. TROUBLESHOOTING (Cont.)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
9. FAN MOTOR (B2) DOES NOT OPERATE.
Disconnect input power before performing internal electrical troubleshooting.
Voltages used can be deadly,
Step 1. Using wiring diagram (fig. 4-21), check electrical connectors P3
and J3, P9
and J9, P12 and
J12,
and individual wires for tightness and continuity.
Tighten, repair, or replace as indicated.
Step 2.
Check operation of
fan motor, relay (K4)
Test relay. (See para 458.) Replace relay if defective.
Step 3. Check operation of fan motor (B2).
Test motor. (See para 464.) Contact direct support maintenance if motor is defective.
Step 4. Check operation of mode selector switch (S1).
Test switch. (See para 4-41.) Replace switch if defective.
10. EXCESSIVE NOISE WHEN COMPRESSOR STARTS.
If a knocking or hammering sound is heard when compressor starts, turn mode
selector switch to OFF, immediately. Such noise is usually caused by liquid
refrigerant in compressor, which can seriously damage or destroy compressor.
Contact direct support maintenance.
11. EXCESSIVELY NOISY OPERATION.
Step 7. Isolate source of noise as near as possible, both by ear and touch.
Listen and feeI at both front and back of cabinet
Step 2. Check fans for looseness or damage, and for rotational clearance.
Tighten loose fans, adjust for rotational clearance, or replace fans. (See para 4-63 and
4-64.)
Step 3. Check all internal components for looseness, vibration, and security.
Tighten, adjust, and secure as necessary.
4-54