Blower Motor: Description and Operation

Blower
The blower draws in passenger compartment air and sends it through the evaporator coil. It consists of a blower fan and an electric motor.

Blower motor
Blower motor speed is controlled by the blower knob and the resistor assembly in the blower unit. When the blower knob 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 position, current flow from 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 second, third, or fourth positions causes the circuit resistance to decrease and the blower motor speed becomes correspondingly faster.