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 - 6. Disconnect heater fan high If +12 VDC is present, go to step

Continued

relay from connector. Check 7. If no voltage is present, repair

for +12 VDC at connector 87. lead 98.

7. Check for continuity between If continuity is indicated, go to

connector 86 and ground for step 8. If no continuity is

both relays.

indicates, repair ground lead.

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

relay from connector. Check 9. If no voltage is present, repair

for +12 VDC at connector 85. lead 71AA.

9. Disconnect lead 98 from heater If +12 VDC is present, go to step

fan control. Check for +12 10. If no voltage is present,

disconnect heater fan power relay.

VDC at lead 98.

Check for continuity in lead 98. If

continuity is indicated, replace

heater fan power relay (WP 0072

00). If no continuity is indicated,

repair lead 98.

10.Disconnect lead 98L from

If +12 VDC is present, go to step

heater fan control. Check for

11. If no voltage is present,

+12 VDC at heater fan control

replace heater fan control (WP

connector (D) with heater fan

0069 00).

control in high mode.

11.Disconnect heater fan high If +12 VDC is present, go to step

relay from connector. Check 12. If no voltage is present, repair

for +12 VDC at connector 85 lead 98L.

with heater fan control in high

mode.

12.Disconnect lead 98T from

If +12 VDC is present, go to step

heater fan motor. Check for

13. If no voltage is present,

+12 VDC at lead 98T with

disconnect heater fan high relay

heater fan control in high mode.

from connector. Check for

continuity in lead 98T between

connector 30 and heater fan

motor. If continuity is indicated,

replace heater fan high relay (WP

0072 00). If no continuity is

indicated, repair lead 98T.

13.Disconnect ground lead from

If continuity is indicated, replace

heater fan motor. Check for

heater fan motor (WP 0211 00). If

continuity between ground lead

no continuity is indicated, repair

and ground.

ground lead.

0010 00-39