Blower Motor: Description and Operation

Description

The blower draws in hot passenger compartment air and sends it through the evaporator coil. It consists of a blower fan and an electric motor. Blower motor speed is controlled by the blower switch and a resistor assembly in the blower unit. When the blower switch is in the OFF position, the motor ground circuit is open and the blower motor does not operate. When the switch is in the first (Low) position, current flow from the blower motor is restricted by the three resistors in the resistor assembly, and the blower motor turns at low speed. Changing the blower switch to the second (M1), third (M2), or fourth (Hi) positions causes the circuit resistance to decrease, and the blower motor speed to become correspondingly faster.

Operation

Blower motor speed is controlled by the blower switch and a resistor assembly in the blower unit. When the blower switch in the OFF position, the motor ground circuit is open and the blower motor does not operate. When the switch is in the first (LO) position, current how to the blower motor is restricted by the three resistors in the resistor assembly, and the blower motor turns at a low speed. Changing the blower switch to the second (M1), third (M2), or fourth (HI) positions causes successive decreases of the circuit resistance, resulting in the blower motor speed becoming correspondingly faster.