Blower Motor: Description and Operation
Normal operation of blower motorBlower 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 (Mid), third (High), or fourth (Super-high) positions causes the circuit resistance to decrease, and the blower motor speed to become correspondingly faster.