Air Delivery

The air valves and vents in the Air Conditioning System are operated by mechanical and vacuum controls. There are no electrical circuits. The functions of the air valves an A/C Evaporator core are described below.

Temperature Valve

The Temperature Valve is controlled by the Temperature Selector in the heater And A/C Control Assembly. With the Temperature Selector in COLD, the valve is in the COOL position. This prevents air from blowing across the Heater Core. With the Selector in any other position, some or all of the air blows across the Heater Core.

A/C Evaporator Core

All air passing through the A/C module moves across the A/C Evaporator Core. When the Compressor is on, the core cools and removes moisture from the air.

Inlet and Outlet Valves

The Outside Air Valve, Slave Valve, A/C Defrost Valve and Mode Valve are moved according to the position of the A/C Mode Selector. The Selector contains vacuum valves or switches. These valves apply and remove vacuum to Vacuum Actuators that move the inlet and outlet valves.

The Outside Air Valve is in position A for every A/C Mode Selector position except MAX. The actuator bellows are expanded which opens the Outside Air Valve and lets outside air into the module.

When the A/C 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 module.

The Slave Valve is in position B for all modes except HEATER and DEF. In position B, air flow through the Heater Core is restricted, allowing maximum cooling in the Air Conditioning modes. When the A/C Mode Selector is moved to HEATER or DEF, vacuum is applied to the Slave Valve Vacuum Actuator, which moves the valve to position A. In this position, air flow through the Heater Core is unrestricted to provide maximum heat output.

The Mode Valve Vacuum Actuator, which controls the Mode Valve, can assume three positions. The Actuator is operated by two bellows and two vacuum switches. With the A/C Mode Selector in MAX, NORM, VENT or DEF, vacuum is applied through the YEL hose. The bellows closest to the YEL hose contracts, moving the Valve to position A. Air flow is directed toward the windshield outlets or A/C- instrument panel outlets and no air flows from the floor outlets.

The Mode Valve Vacuum Actuator has vacuum applied through the RED hose with the A/C Mode Selector in HEATER. The bellows closest to the RED hose contracts. The Valve is pulled to position C. All air is directed to the floor outlets.

With the A/C Mode Selector in BI-LEVEL (position 4), no vacuum is applied to either side of the Actuator. Both bellows expand part way. The Mode Valve moves to position B. Part of the air flows out the floor outlets. The rest of the air flows out the A/C-instrument panel outlets.

The A/C Defrost Valve is controlled by the A/C Defrost Valve Vacuum Actuator. With the A/C Mode Selector in any position but OFF, HEATER or DEF, vacuum is applied to the Actuator. The bellows contracts and the A/C Defrost Valve is pulled to position B. All air flows out the A/C-instrument panel outlets.

With the A/C Mode Selector in DEF, vacuum is removed from the A/C Defrost Valve Vacuum Actuator. The bellows extends and the Valve moves to position A. All air passes out the windshield outlets.