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 installed 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 -   The vacuum control motors:

• direct system airflow to the vehicle interior as determined by the function selector switch.

Fig 1: Climate Control Vacuum Components

Courtesy of FORD MOTOR CO.

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