Air Door Actuator / Motor: Description and Operation

Air Valve Position Chart:

Air Delivery Vacuum Diagram:

Description
The air valves that control the heating and air conditioning air flow are operated by vacuum actuators. The valves that apply or vent vacuum to these actuators are solenoid operated. The valves are located in the Heater and A/C Programmer and are powered by a Solid State unit in the Heater and A/C Programmer. Push-button switches in the Heater and A/C Control Assembly signal the Heater and A/C Programmer to operate the air valves.

Two temperature variable resistors are connected to the Heater and A/C Programmer to provide temperature information. The In-Car Sensor indicates the inside air temperature at which the air conditioning system can warm or cool the air to bring it to the selected temperature. The Ambient Sensor indicates the outside air temperature. The difference between the two sensor temperatures is used by the Heater and A/C Programmer to determine the setting of the Temperature Valve Control output.

The function of the vacuum and air valves are described below.

Mode Valve
The Mode Valve is moved by the Mode Valve Vacuum Actuator. This device has two actuators, each operated by a separate valve. In the BI-LEVEL push-button position, neither valve is energized, and the Mode Valve is in its middle position. This sends air to both the A/C Outlets and the Heater Outlets on the floor. If the Up Valve is operated, the vacuum actuator moves the valve to position C (refer to the images). This happens when the HEATER push-button has been pressed.

When the Down Valve is operated, the other vacuum actuator moves the valve to position A. This is the position for MAX, NORM, VENT, and DEF.


A/C Defrost Valve
The A/C Defrost Valve is in position B for all the cooling functions. In these functions, the A/C Defrost Valve Vacuum Actuator is energized and vacuum is applied to its vacuum actuator. When the DEF or HEATER push-button is depressed, the valve is de-energized. It vents the vacuum to the atmosphere and the valve moves to position A.

Temperature Valve
The Temperature Valve is controlled by the Temperature Valve Control Motor. With the valve in the COOL position, air is blocked from passing through the Heater Core. The motor can adjust the valve to any position between COOL and WARM. In the WARM position, all of the air flows through the Heater Core for maximum heat. The Temperature Valve controls the amount of warming of the air that has passed through the A/C Evaporator Core.

Outside Air Valve
The Outside Air Valve is at position A, permitting outside air to enter in all the push-button selector positions except MAX. In MAX, the Outside Air Valve is at position B, recirculating the inside air to get maximum cooling. In this position, the Outside Air Valve Vacuum Actuator is energized, applying vacuum through the Vacuum Delay Porous Plug. This plug has a high resistance to air flow so that the actuator and valve move slowly after the valve has opened.