Manual Climate Control

MANUAL CLIMATE CONTROL

The manual climate control 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 operation.

Control System Inputs
The climate control assembly has three system control inputs.

Function Selector Switch
The function selector switch combines a vacuum selector valve that determines air distribution and an electrical switch to supply battery voltage to the A/C compressor circuit and the blower motor circuit. When the function selector switch is in the MAX A/C, DEFROST, or FLOOR/DEFROST positions, the A/C compressor will be operational regardless of the A/C request switch status.

Climate Control Assembly
The climate control assembly integrates the temperature control switch, A/C request button and rear defog switch into a single unit.

The temperature control switch setting determines air temperature. Temperature selection is accomplished with a potentiometer (temperature control switch) connected to the temperature blend door actuator. Movement of the temperature control switch from COOL (blue) to WARM (red) causes a corresponding movement of the temperature blend door and determines the air discharge temperature that the air distribution system will maintain. The temperature control switch is an integral part of the manual climate control assembly and cannot be separately replaced.

The A/C request switch determines A/C compressor operation, except when the function selector switch is in the OFF, MAX, DEFROST, or FLOOR/DEFROST positions. The A/C request switch is an integral part of the manual climate control assembly and cannot be separately replaced.

The rear defog button signals activation of the heated backlight and heated mirrors. The rear defog button is an integral part of the manual climate control assembly and cannot be separately replaced.

Blower Motor Switch
The blower motor switch controls blower motor speed by adding or bypassing resistors in the blower motor switch resistor in all function selector switch positions except OFF.

Control System Outputs
The climate control system has five system outputs.

Blower Motor Resistor
The blower motor resistor:
- is located on the heater core and evaporator core housing near the blower motor.
- has three resistor elements mounted on the resistor board to provide four 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.
- has an overheating device (thermal limiter) that will open the resistor coil when the temperature reaches approximately 184° C (363°F), interrupting the blower motor operation in all speeds except high.
- is serviced as an assembly. The thermal limiter cannot be reset and is not serviceable.

Temperature Blend Door Actuator
The temperature blend door actuator:
- is located on the heater core and evaporator core housing.
- moves the temperature blend door on command of the temperature control switch.
- contains a reversible electric motor.

Vacuum Control Motors
The four vacuum control motors:
- direct system airflow to the vehicle interior as determined by the function selector switch.

Heater Control Valve Vacuum Switch
The heater control valve vacuum switch to control operation of the heater control valve. The heater control valve vacuum switch:
- is mounted on the RH side of the heater core and evaporator core housing just below the defrost door vacuum control motor.
- is actuated by an arm attached to the temperature blend door RH pivot shaft.
- applies vacuum to the heater control valve when the temperature blend door is in the full COOL position.