TM 10-3930-669-20 10.  HEATER DOES NOT BLOW WARM OR HOT AIR (CONT). KNOWN INFO Cool air passes from heater duct. Heater temperature control OK. POSSIBLE PROBLEMS Heater valve faulty. Heater cable faulty. Engine oil cooler thermostat faulty. KNOWN INFO Cool air passes from heater duct. Heater temperature control OK. Heater valve OK. POSSIBLE PROBLEMS Heater cable faulty. Engine oil cooler thermostat faulty. TEST OPTIONS Visual inspection. REASON FOR QUESTION If heater valve is faulty, air temperature will not adjust. TEST OPTIONS Visual inspection. REASON FOR QUESTION If heater cable is faulty, air temperature will not adjust. 2-118