ARMY TM 9-4120-380-14
AIR FORCE TO 35E9-136-21
Table 4-2. Unit Maintenance Troubleshooting - Continued
Test or Inspection
7. CONDENSER FAN MOTOR (B3) DOES NOT OPERATE - Continued
Step 2. Check operation of fan motor contactor (K3).
Step 3. Check operation of fan motor (B3).
Step 4. Check operation of MODE SELECT switch (S1).
8. EXCESSIVE NOISE WHEN COMPRESSOR STARTS
If a knocking or hammering sound is heard when compressor starts, turn MODE
SELECT switch to OFF immediately. Such noise is usually caused by liquid
refrigerant in compressor, which can seriously damage or destroy compressor.
Step 1. Turn compressor OFF, wait a minute and turn to AUTO.
If compressor continues to knock, turn compressor OFF immediately and contact Direct Support
9. EXCESSIVE NOISE OPERATION
Step 1. Isolate source of noise as near as possible, both by ear and touch Listen and feel at both the front and
back of the cabinet.
Step 2. Check fans for looseness or damage and for rotational clearance.
Step 3. Check all internal components for looseness, vibration and security.
Tighten, adjust and secure as necessary.