Part 3 of 6

BLOWER MOTOR SWITCH - FRONT
The heater-A/C blower motor is controlled by a four position rotary-type blower motor switch, mounted in the heater-A/C control panel. The switch allows the selection of one of four blower motor speeds, but can only be turned OFF by selecting the OFF position with the heater-A/C mode control switch knob.

The blower motor switch directs the blower motor ground path through the mode control switch to the blower motor resistor, or directly to ground through the high speed blower motor relay, as required to achieve the selected blower motor speed.

The blower motor switch cannot be repaired and, if faulty or damaged, the entire heater-A/C control unit must be replaced. The blower motor switch knob is serviced separately.

MODE DOOR ACTUATOR - FRONT
The mode door actuator is a reversible, 12-volt Direct Current (DC), servo motor. The single mode door actuator is located on the driver side end of the heater-A/C housing unit, close to the top of the distribution housing. The mode door actuator is mechanically connected to the mode door. The mode door actuator is interchangeable with the actuators for the blend air door(s) and the recirculation air door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Two integral mounting tabs allow the actuator to be secured with two screws to the heater-A/C unit housing. Each actuator also has an identical output shaft with splines that connects it to the linkage that drives the mode door. The mode door actuator does not require mechanical indexing to the mode door linkage, as it is electronically calibrated by the heater-A/C control module. The mode door actuator cannot be adjusted or repaired and, if damaged or faulty, it must be replaced.

The mode door actuator is connected to the heater-A/C control module through the vehicle electrical system by a dedicated two-wire take out and connector of the HVAC wire harness. The mode door actuator can move the mode door in two directions. When the heater-A/C control module pulls the voltage on one side of the motor connection high and the other connection low, the mode door will move in one direction. When the module reverses the polarity of the voltage to the motor, the mode door moves in the opposite direction. When the module makes the voltage to both connections high or both connections low, the mode door stops and will not move. These same motor connections also provide a feedback signal to the heater-A/C control module. This feedback signal allows the module to monitor the operation and relative position of the mode door actuator and the mode door. The heater-A/C control module learns the mode door stop positions during the calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the mode door actuator circuits. The mode door actuator can be diagnosed using a DRB III scan tool. Refer to the appropriate diagnostic information.

RECIRCULATION DOOR ACTUATOR - FRONT
The recirculation door actuator is a reversible, 12-volt Direct Current (DC), servo motor. The single recirculation door actuator is located on the passenger side end of the heater-A/C housing unit, on the bottom of the lower intake air housing. The recirculation door actuator is mechanically connected to the recirculation air door. The recirculation door actuator is interchangeable with the actuators for the blend air door(s) and the mode door. Each actuator is contained within an identical black molded plastic housing with an integral wire connector receptacle. Two integral mounting tabs allow the actuator to be secured with two screws to the lower intake air housing. Each actuator also has an identical output shaft with splines that connects it to the linkage that drives the recirculation air door. The recirculation door actuator does not require mechanical indexing to the recirculation air door; as it is electronically calibrated by the heater-A/C control module. The recirculation door actuator cannot be adjusted or repaired and, if damaged or faulty, it must be replaced.

The recirculation door actuator is connected to the heater-A/C control module through the vehicle electrical system by a dedicated two-wire take out and connector of the HVAC wire harness. The recirculation door actuator can move the recirculation door in two directions. When the heater-A/C control module pulls the voltage on one side of the motor connection high and the other connection low, the recirculation air door will move in one direction. When the module reverses the polarity of the voltage to the motor; the recirculation air door moves in the opposite direction. When the module makes the voltage to both connections high or both connections low, the recirculation air door stops and will not move. These same motor connections also provide a feedback signal to the heater-A/C control module. This feedback signal allows the module to monitor the operation and relative position of the recirculation door actuator and the recirculation air door. The heater-A/C control module learns the recirculation air door stop positions during the calibration procedure and will store a Diagnostic Trouble Code (DTC) for any problems it detects in the recirculation door actuator circuits. The recirculation door actuator can be diagnosed using a DRB III scan tool. Refer to the appropriate diagnostic information.

Fig. 1 Rear Blower Motor Wheel/Resistor:

BLOWER MOTOR RESISTOR BLOCK - REAR
The blower motor resistor for the optional rear A/C unit is located within the unit housing. The resistor has multiple resistor wires, each of which will change the resistance in the blower motor ground path to change the blower motor speed. The blower motor switch located in the A/C control head directs the ground path through the correct resistor wire to obtain the selected blower motor speed.

With the blower motor switch in the lowest speed position, the ground path for the motor is applied through all of the resistor wires. Each higher speed selected with the blower motor switch applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed. When the blower motor switch is in the highest speed position, the blower motor resistor is bypassed and the blower motor receives a direct path to ground.

The blower motor resistor cannot be repaired and, if faulty or damaged, it must be replaced.

REAR HVAC CONTROL
The optional rear heater-A/C unit blower motor is controlled by a four position rotary-type blower motor switch, mounted by a snap fit in a hole in the headliner over the right front seat back. The switch allows the selection of one of three blower motor speeds and an OFF Position when the front control is set to rear unit operation otherwise the front unit controls both front and rear operation. The blower motor switch directs the blower motor ground path through the blower motor resistor.

The blower motor switch cannot be repaired and, if faulty or damaged, the entire switch unit must be replaced. The blower motor switch has a replaceable incandescent-type illumination lamp bulb.

BLOWER MOTOR - FRONT
The blower motor and blower wheel are located in the passenger side end of the heater-A/C housing, below the glove box. The blower motor controls the velocity of air flowing through the heater-A/C housing by spinning a squirrel cage-type blower wheel within the housing at the selected speed. The blower motor and blower wheel can only be serviced with the heater-A/C housing removed from the passenger compartment.

The blower motor will only operate when the ignition switch is in the ON position, and the heater-A/C mode control switch knob is in any position, except OFF. The blower motor receives a fused battery feed through the blower motor relay (Voltage Reduction Relay or VRR) whenever the ignition switch is in the ON position.

The blower motor battery feed circuit is protected by a fuse in the Power Distribution Center (PDC). The blower motor relay control circuit is protected by a fuse in the junction block. Blower motor speed is controlled by regulating the ground path through the heater-A/C mode control switch, the blower motor switch, the blower motor resistor, the blower motor relay (VRR), and the high speed blower motor relay.

The blower motor and blower motor wheel cannot be repaired and, if faulty or damaged, they must be replaced. The blower motor and blower wheel are each serviced separately.