TM 9-4120-403-14
TABLE 4-2. UNIT TROUBLESHOOTING (cont)
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Step 3. Check operation of fan toggle switch (S7).
Switch from LO to HI SPEED. If no change results, test switch. (See para 4-29.)
Replace defective switch.
Step 4. Check operation of time delay relay (K9).
Step 5. Check operation of temperature control thermostat (S 1).
Test thermostat. (See para4-28.) Inspect sensing bulb and capillary for damage or
leakage. Replace if defective. If malfunction still exists, notify your supervisor.
7. NO HEAT IN EITHER HI HEAT OR LOW HEAT MODE.
Step 1. Check operation of heater thermostat (S3).
Test thermostat. (See para 4-54.) Replace if defective.
Step 2. Check operation of mode selector switch (S).
Test switch.
If malfunction still exists, notify your
supervisor.
8. HEAT IN HI HEAT MODE, BUT NOT IN LO HEAT MODE.
Step 1. Check operation of temperature control thermostat (S 1).
Test thermostat. (See para 4-28.) Inspect sensing bulb and capillary for damage or leakage.
Replace if defective.
Step 2. Check operation of mode selector switch (S).
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