Insufficient Or No Heat

Observe the servo vacuum with the temperature lever at 85° F. If 3 in. Hg. or lower, check for hot heater hoses to and from the heater core and that the servo positions the blend door in the full heat position. If over 3 in. Hg., disconnect the line from the servo and note the discharge temperature. If heat is available, check the Automatic Temperature Control (ATC) temperature sensor cable adjustment. If OK, replace the ATC temperature sensor. If no heat is available, correct the fault in the cooling system.