Control Components

Control Components

The manual climate control system heats or cools the vehicle interior depending on the function selector switch position and the temperature selected. The function selector switch position determines heating or cooling and air distribution. The temperature blend control setting determines air temperature.

The manual climate control system components are used to select:

- air inlet source (outside or recirculated).
- blower motor speed.
- discharge air temperature (temperature blend).
- discharge air location (defrost, panel, floor).
- A/C compressor clutch operation.


Control System Inputs

The climate control assembly has 3 system controls:


Function Selector Switch

The function selector switch combines a vacuum selector valve with 2 electrical switches to supply battery voltage (B+) to the A/C clutch circuit and the blower motor speed control circuit.


Temperature Control Switch

Temperature selection is accomplished with a potentiometer connected to the temperature blend door actuator. Movement of the temperature control switch from COOL (blue) to WARM (red) causes a corresponding movement on the air temperature that the air system will maintain.


Blower Motor Switch

The blower motor switch controls blower motor speed by adding or by passing resistors in the heater blower motor switch resistor.


Control System Outputs

The climate control system has 3 system outputs:


Blower Motor Resistor

The blower motor resistor has 3 resistor elements mounted on the resistor board to provide 4 blower motor speeds. Depending on the blower motor switch position, series resistance is added or bypassed in the blower motor circuit to decrease or increase blower motor speed. The blower motor resistor has an overheating device (thermal limiter) that opens the resistor coil when the temperature reaches approximately 184°C (363°F), interrupting the blower motor operation in all speeds except high. The thermal limiter cannot be reset and is not serviceable.

Temperature Blend Door Actuator

The temperature blend door actuator moves the temperature blend door on command from the temperature control switch using a reversible electric motor. The temperature blend door actuator contains an internal controller that will recognize the temperature control switch signal and drive the temperature blend door to the desired position.

The temperature blend door actuator is located on the heater core and evaporator core housing near the glove compartment.

Vacuum Control Motors

The vacuum control motors move the airflow mode doors to direct system airflow to the vehicle interior as determined by the function selector switch.