Table 1. Troubleshooting Procedures - Continued

TM 9-4120-425-14&P

DIRECT SUPPORT TROUBLESHOOTING PROCEDURES - Continued

0047-00

Table 1. Troubleshooting Procedures - Continued

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

Tighten loose connections.

11. LOW HEAT OR NO HEAT

Check heater wiring and control

circuit for loose connections or

Replace or repair broken wires.

broken wires.

(Refer to WP 0027-00, WP 0028-

00, WP 0034-00 through WP

0038-00.)

Replace faulty switch. (Refer to WP

Check continuity of mode

0034-00 and WP 0035-00.)

selector switch, temperature

selector switch and thermostat.

(Refer to WP 0034-00 and WP

0035-00.)

Replace faulty heating elements.

Disconnect and remove heater

(Refer to WP 0028-00.)

elements, and apply 115-volt AC

power to check for open circuit in

element or check resistance.

Element should heat.

Replace faulty switch. See WP 0027-

Check continuity of two heater

00.

cutout switches at room

temperature. Continuity should

exist. (Refer to WP 0027-00.)

Replace faulty relay. (Refer to WP

Disconnect heater relay. Apply

0036-00.)

24-28 volts to actuate relay and

check continuity at power

terminals. Continuity should

exist. (Refer to WP 0036-00.)

Repair or replace faulty fan or motor.

Check operation of evaporator

(Refer to WP 0030-00.)

fan and motor. (Refer to WP

0030-00.)

END OF TASK

0047-00-7