Blower Motor Resistor: Description and Operation

Blower Motor Resistor:

The blower motor resistor is located in the cowl, at the base of the windshield. There are two different blower motor resistors depending on whether the vehicle is equipped with A/C or not.

The blower motor resistor is mounted to the dash panel within the engine compartment. The resistor consists of a molded plastic mounting plate with an integral wire connector receptacle. Concealed behind the mounting plate are coiled resistor wires contained within a protective stamped steel cage. The blower motor resistor is accessed for service by removing the cowl top screen.

The blower motor resistor is connected to the vehicle electrical system through a dedicated take out and connector of the vehicle harness. The blower motor resistor has multiple resistor wires, each of which will reduce the current flow through the blower motor to change the blower motor speed. The blower motor switch directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed.

With the blower motor switch in the lowest speed position, the ground path for the motor is applied through all of the resistor wires. Each higher speed selected with the blower motor switch applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed. When the switch is in the highest speed position, blower motor resistor is bypassed and the blower motor receives a direct path to ground.

The blower motor resistor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.