REDUCED HEATING CAPACITY. - TM-5-4120-393-140094

TM 5-4120-393-14

Table 4-2. Unit Maintenance Troubleshooting

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

b. Test switch in TEMPerature control thermostat. (See para 4-37.) Replace entire

control if defective.

Step 4.

Check operation of mode selector switch (S).

Test switch. (See para 4-38.) Replace switch if defective.

11. REDUCED HEATING CAPACITY.

Step 1.

Check airflow out of conditioned air (evaporator) discharge grille. If airflow volume is low:

a. Adjust conditioned air (evaporator) intake grille louvers.

b. Clean and service, or replace, conditioned air filters. (See para 4-30.)

c. Clean and service, or replace, mist eliminator. (See para 4-32.)

d. Clean evaporator coil and entire evaporator section. (See para 4-62.)

Step 2.

Check adjustment of fresh air damper and/or CBR filter, if installed

Adjust properly.

Step 3.

Check operation of heater thermostat (S3).

WARNING

Disconnect input power before performing internal electrical troubleshooting.

Voltages used can be deadly.

Test thermostat. (See para 4-57.) Replace thermostat if defective.

Step 4.

Check operation of individual heater elements (HR1, 2, 3, 4, 5, 6).

Test each element. (See para 4-58.) Replace defective elements.

Step 5.

Check operation of TE MPerature control thermostat (S1).

a. Inspect sensing bulb and capillary for damage or leakage. Replace entire control if bulb

is damaged or leaking.

b. Test switch in TEMPerature control thermostat (S1). (See para 4-37.) Replace entire

control if defective.

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