Blower Motor: Description and Operation

CIRCUIT OPERATION
Manual A/C
With the ignition switch is in the RUN position, power flows from the 25 amp fuse located in the junction block, cavity 21, to the blower motor. Blower motor speed is controlled by the fan control switch located in the A/C-Heater control, and by the resistor block.

Blower motor LOW speed operation is accomplished on the C4 circuit. When the control switch is moved to the LOW speed position, current flows from the C1 circuit to the blower motor resistor. Power flows from the resistor, on circuit C1, through the blower motor back to the resistor. Voltage is passed through the resistor to circuit C4. Circuit C4 connects from the resistor block to the fan control switch. Power flows through the switch to the Z1 circuit. The Z1 circuit terminates at a grounding point located at the instrument panel left side cowl.

The operation of blower motor M1 and M2 speed operations is the same as the LOW speed except that circuit C5 is used for the M1 speed, and circuit C6 is used for the M2 speed operation.

Blower motor HIGH speed operation is accomplished on the C7 circuit. There are no resistors used in the HIGH speed mode.

ATC Power Module/Blower Motor (ATC)
Power for the ATC power module, and the blower motor, is supplied on circuit C1. This circuit is protected by a 25 amp fuse located in cavity 21 of the junction block. Power for the fuse is supplied on circuit A22 from the ignition switch. This circuit is HOT in the RUN position only.

Power for the A22 circuit is supplied by circuit A2 from the Power Distribution Center (PDC). The A2 circuit is protected by a 40 amp fuse located in cavity J of the PDC.

Ground for the power module is supplied on circuit Z1. This circuit terminates at the Airbag Control Module (ACM) bracket.

Circuit C56 is used for blower motor speed control. This circuit connects from the Body Control Module (BCM) to the power module.

Blower motor speed is determined by the BCM based on the position of the fan switch located in the control head.