Table 1. Standard Heater Circuit Troubleshooting Procedures.

TM 9-2320-303-24-1

Table 1. Standard Heater Circuit Troubleshooting Procedures.

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

Heater Fan Does Not Operate In Any Speed. 1. Check heater fan 30A fuse.

If defective, replace 30A fuse (WP

2. Check start/auxiliary 15A fuse. If defective, replace 15A fuse (WP

3. Remove heater fan 30A fuse. If +12 VDC is present, go to step

Check for +12 VDC at lead 14 4. If no voltage is present, repair

fuse connector.

lead 14 to 12-volt constant power

bus.

4. Remove start/auxiliary 15A If +12 VDC is present, go to step

fuse. Check for +12 VDC at 5. If no voltage is present, repair

lead 71A fuse connector.

lead 71A.

5. Disconnect heater fan power If +12 VDC is present, go to step

relay from connector. Check 6. If no voltage is present, repair

for +12 VDC at connector 30. lead 98.