TM 5-2420-230-24-1
Table 3-6. Unit Troubleshooting Table. -- Continued
Malfunction
Test or Inspection
Corrective Action
49.2
NO HEAT FROM AUXILIARY DEFROSTER AND CABIN HEATER.
Hot parts and fluids can burn personnel. If vehicle has been operating, let engine cool before
starting work. Avoid contact with hot fluid when removing hoses or fittings. Failure to comply
may result in serious injury or death to personnel.
Coolant may damage the skin. Wear protective equipment and avoid skin contact when handling
coolant.
Step 1.
Check thermostat (1) to ensure it is functioning correctly (Para L-11).
If thermostat (1) is missing or not functioning correctly, replace thermostat (Para L-11).
Step 2.
Check auxiliary defrost coolant hoses (2) and evaporator coolant hoses (3) for clogging, collapsing, or
leaking.
If coolant hoses (2) and (3) are clogged, collapsed, or leaking, replace hoses (Para 13-36 and
Step 3.
Check auxiliary defroster heater core (4) for damage, blockage, or leaking (Para 13-36).
If auxiliary defroster heater core (4) is damaged, blocked, or leaking, replace heater core
If auxiliary defroster heater core (4) is not damaged, blocked, or leaking, replace evaporator
Change 1
