Air Delivery and Temperature Controls

Air Position Valve Table:

AIR DELIVERY CIRCUIT OPERATION
The air valves and vents in the A/C system are operated by mechanical and vacuum controls. There are no electrical circuits. The functions of the plenum valves are described below.

TEMPERATURE VALVE
The Temperature Valve is controlled by the temperature selector in the Heater and A/C 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.

A/C HEATER VALVE
The A/C Heater Valve Vacuum Actuator, which controls the A/C Heater Valve, is bi-directional. The actuator is operated by two bellows and two vacuum switches. With the Mode Selector in MAX, NORM or VENT, vacuum is applied through the YELLOW hose. The bellows closest to the YELLOW hose contract pulling the A/C Heater Valve to position A. No air flows from the Floor Outlets.

The A/C Heater Valve Vacuum Actuator has vacuum applied through the RED hose with the Mode Selector in OFF, HTR, or DEF. The bellows closest to the RED hose contract. The A/C Heater Valve is pulled to position C. All air is directed to the Floor Outlets.

With the Mode Selector in B/L (position 4), no vacuum is applied to either side of the A/C Heater Valve Vacuum Actuator. Both bellows extend part way. The A/C Heater Valve moves to position B. Part of the air flows out the Floor Outlets. The rest of the air flows out the Panel Outlets.

A/C DEFROST VALVE
The A/C Defrost Valve is controlled by the A/C Defrost Valve Vacuum Actuator. With the Mode Selector in any position but DEF (position 7), vacuum is applied to the actuator. The bellows contract and the A/C Defrost Valve is pulled to position B. All air flows out the Panel Outlets.

No vacuum is applied to the A/C Defrost Valve Vacuum Actuator with the Mode Selector in DEF. The bellows extend and the A/C Defrost Valve moves to position A. All air passes out the Windshield Outlets.

OUTSIDE AIR VALVE
The Outside Air Valve Vacuum Actuator has no vacuum applied for every Mode Selector position except MAX (position 2). The actuator bellows are expanded. The Outside Air Valve is in position A. This opens the Outside Air Inlet and lets outside air into the plenum.

When the Mode Selector is moved to MAX, vacuum is applied to the Outside Air Valve Vacuum Actuator. The bellows are drawn in and the valve is moved to position B. Air from inside the car is pulled into the plenum.