Control Components

CONTROL COMPONENTS

The manual climate control system heats or cools (if equipped with A/C) the vehicle interior depending on the function selector position and the temperature selected. Function selector position determines heating or cooling (if equipped with A/C) and air distribution. The temperature blend control setting determines air temperature.

The manual climate control components are used to:
- select air inlet source (outside or recirculated).
- select blower motor speed.
- select discharge air temperature (temperature blend).
- select discharge air location (DEFROST, PANEL, FLOOR).
- select A/C compressor clutch operation (if equipped with A/C).

Control System Inputs

Climate Control Assembly
The climate control assembly has 3 system controls:
- The function selector switch combines a vacuum selector valve with 2 electrical switches to supply battery positive voltage to the A/C clutch circuit (if equipped with A/C) and the blower motor control circuit.
- The temperature selection is accomplished with a potentiometer connected to the electric temperature blend door actuator that controls positioning of the temperature blend door. Movement of the control knob from COOL (blue) to WARM (red) causes a corresponding movement on the air temperature control door and determines the temperature that the system will maintain.
- The blower motor switch controls blower motor speed by adding or bypassing resistors in the blower motor resistor.

Control System Outputs

Blower Motor Resistor
The blower motor resistor has the following features:
- The assembly is located on the passenger side of the vehicle on the evaporator housing.
- Three resistance elements are mounted on the resistor board to provide 4 blower motor speeds.
- Depending on the blower switch position, series resistance is added or bypassed in the blower motor circuit to decrease or increase blower motor speed.
- An overheating protective device (thermal limiter) will open the resistor coil circuit when the temperature reaches 121°C (250°F) interrupting the blower motor operation in all speeds except HI.
- The thermal limiter cannot be reset and is not serviceable.

Vacuum Control Motors
The 3 vacuum control motors:
- are actuated by vacuum from the function selector switch.
- position the airflow mode doors to direct system airflow to the vehicle's interior as determined by the function selector switch setting.

Temperature Blend Door Actuator
The temperature blend door actuator:
- is located on the RH side of the heater core housing.
- moves the temperature blend door on command from the temperature control switch.