Blower Motor Resistor: Description and Operation

BLOWER MOTOR RESISTOR

The blower motor resistor adjusts the blower motor speed based on the blower motor switch setting. The blower motor resistor contains 3 resistor coils in series. The end of each resistor coil is wired to a setting in the blower motor switch. Voltage is available at the blower motor at all times when the ignition is in the RUN position and the function selector is not OFF. The ground side of the circuit then continues to the blower motor resistor. The blower motor switch will allow a path to ground with the addition of 1, 2 or 3 coils in the blower motor resistor to the circuit. When the blower motor switch is in the MED HI position, the blower motor switch will add a path to ground through one coil in the blower motor resistor. When the blower motor switch is in the MED LO position, the blower motor switch will add a path to ground through 2 coils (in series) in the blower motor resistor. When the blower motor switch is in the LO position, the blower motor switch will add a path to ground through 3 coils (in series) in the blower motor resistor. When the blower motor switch is in the HI position, the blower motor resistor is bypassed.