Control Components

CONTROL COMPONENTS

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 3 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, A/C, A/C RECIRC (Hybrid), FLOOR/DEFROST or DEFROST positions, the A/C compressor will be operational. The function selector switch can be replaced separately from the climate control head unit.

Temperature Control Switch
The temperature control switch setting determines the air temperature. Temperature selection is accomplished through a cable connected to the temperature blend door. 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 can be replaced separately from the climate control head unit.

Blower Motor Switch
The blower motor switch controls the blower motor speed by adding or bypassing resistors in the blower motor switch resistor in all function selector switch positions except OFF. The blower motor switch can be replaced separately from the climate control head unit.

Control System Outputs
The climate control system has 5 system outputs:

Blower Motor Resistor
The blower motor resistor:
- is located on the evaporator core housing behind the glove compartment.
- 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.
- 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 replaced as an assembly. The thermal limiter cannot be reset and cannot be repaired.

Blower Motor Relay
The blower motor relay supplies voltage to the blower motor and is activated when the key is ON and the function selector switch is in any position besides OFF. The blower motor relay is located under the instrument panel next to the steering column.

Temperature Blend Door Actuator
The temperature blend door actuator:
- is connected between the temperature control switch and the temperature blend door.
- moves the temperature blend door on command of the temperature control switch.

Vacuum Control Motors

Climate Control Vacuum Components:

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

A/C Compressor Clutch Relay
The A/C compressor clutch relay supplies voltage to the A/C compressor clutch and is located in the battery junction box (BJB). The powertrain control module (PCM) can interrupt the A/C compressor operation through the A/C compressor clutch relay under the following conditions:
- During engine start-up
- Wide open throttle (WOT)
- Low engine idle conditions
- Excessively high engine temperatures