TM 9-4120-399-14
Table 4-3. Unit Troubleshooting. (Continued).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
REDUCED HEATING CAPACITY. (Continued).
5.
Check operation of temperature control thermostat switch (S1).
Step 6.
Set control to fully decrease then, if condition improves, adjust
properly.
If condition does not improve, replace temperature control thermostat
switch per para. 4-43.
Check operation of heater thermostat cut-out switch (S3).
Step 7.
Test and replace defective thermostat cut-out switch per para.
Check individual heating elements (HR1 through HR6).
Step 8.
Replace defective heating element per para. 4-27.
Check for loose or damaged wires and terminals.
Step 9.
WARNING
i n p u t power before
Disconnect
internal
electrical
performing
troubleshooting. Voltages used can
be deadly.
Tighten loose or damaged terminals. Repair or replace damaged
wires.
NO HEAT IN EITHER HI HEAT OR LO HEAT MODE.
6.
Step 1.
Check for loose or damaged electrical connectors, or damaged wires
in wiring harnesses.
WARNING
Disconnect input power before
performing
internal
electrical
troubleshooting. Voltages used can
be deadly.
Tighten or replace loose or damaged connectors or repair damaged
wires.
4-30
