Heater symptom
Thread Starter
Pro
Joined: Dec 2003
Posts: 649
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From: Huntsville Alabama
Heater symptom
I have a 1996 with the standard AC/ heat unit and the other morning I got in it and went to turn teh heat on and teh selector slider was loose when I moved it and I do not think teh heat is working. Have any of you seen this problem?
Burning Brakes
Joined: Aug 2007
Posts: 792
Likes: 16
From: Austin Tx
With the Ignition "ON," voltage is applied through the A/C Fuse to the HVAC Control Assembly. The operating mode of the system is determined by switches on the front panel. Output grounds to the HVAC Solenoid Assembly determine which air valves are to be operated.
The Temperature Valve is controlled by the Temperature Lever in the HVAC Control Assembly With the selector in "COLD," the valve is in the "COLD" position. This prevents air from blowing across the Heater Core. With the selector in any position but "COLD," the Temperature Valve is open. According to the selector position, some or all of the air blows across the Heater Core.
When the Front Mode Valve Vacuum Actuator receives vacuum (only in "HEATER" Mode) the Front Mode Valve is pulled to position B. This prevents any air from flowing to the A/C and Defroster Outlets and forces it to go to the Heater Outlets. In any other mode, the Front Mode Valve is in position A, blocking the Heater Outlets.
The Rear Mode Valve is controlled by the Rear Mode Valve Vacuum Actuator. When the Mode Selector is in "MAX," "NORM," "VENT" or "DEFROST," vacuum is applied to the Rear Mode Valve Vacuum Actuator which moves the Rear Mode Valve to position A. This allows air to flow to both the A/C and the Heater Outlets. In any other mode, the Rear Mode Valve is in position B.
The Temperature Valve is controlled by the Temperature Lever in the HVAC Control Assembly With the selector in "COLD," the valve is in the "COLD" position. This prevents air from blowing across the Heater Core. With the selector in any position but "COLD," the Temperature Valve is open. According to the selector position, some or all of the air blows across the Heater Core.
When the Front Mode Valve Vacuum Actuator receives vacuum (only in "HEATER" Mode) the Front Mode Valve is pulled to position B. This prevents any air from flowing to the A/C and Defroster Outlets and forces it to go to the Heater Outlets. In any other mode, the Front Mode Valve is in position A, blocking the Heater Outlets.
The Rear Mode Valve is controlled by the Rear Mode Valve Vacuum Actuator. When the Mode Selector is in "MAX," "NORM," "VENT" or "DEFROST," vacuum is applied to the Rear Mode Valve Vacuum Actuator which moves the Rear Mode Valve to position A. This allows air to flow to both the A/C and the Heater Outlets. In any other mode, the Rear Mode Valve is in position B.
