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 three system controls:

Function Selector Switch
The function selector switch combines a vacuum selector valve with two 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 electric blend door. 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
Heater Blower Motor Switch Resistor
The heater blower motor switch resistor has the following features:
- The assembly is located in the passenger compartment on the evaporator housing next to the blower motor assembly.
- Three resistor elements are mounted on the resistor board to provide four blower motor speeds.
- Depending on the heater blower motor switch position, series resistance is added or bypassed in the A/C blower motor circuit to decrease or increase A/C blower motor speed.
- An overheating device (thermal limiter) will open the resistor coil when the temperature reaches 121° C (250° F) interrupting the blower motor operation in all speeds except high.
- The thermal limiter cannot be reset and is not serviceable

A/C Electronic Blend Door Actuator
The A/C electronic blend door actuator is located on the rear of the A/C evaporator housing.
- Its function is to move the air temperature blend doors on command from the temperature control switch.
- The A/C electronic blend door actuator contains a reversible electric motor and a potentiometer. The potentiometer wiper is connected to the actuator output shaft and moves with the output shaft to indicate the position of the air temperature blend door.

Vacuum Control Motors
The vacuum control motors
- are located on the A/C evaporator housing, A/C recirculating air duct and heater air plenum chamber.
- direct system airflow to the vehicle interior as determined by the function selector switch.