Blower Motor Resistor: Description and Operation

Front Blower Motor Resistor

Description






A blower motor resistor is used on vehicles equipped with the front manual temperature control HVAC system. Vehicles equipped with the front automatic temperature control heating-A/C system use a blower motor power module, instead of the blower motor resistor. Refer to => [ Front Blower Motor Power Module ] Description and Operation.

The front blower motor resistor is mounted to the rear of the HVAC housing, on the passenger side of the vehicle. The blower motor resistor consists of a molded plastic mounting plate (1) with an integral wire connector receptacle (3). Concealed behind the mounting plate are resistors located between a two-piece stamped steel base (2).

The blower motor resistor is accessed for service from underneath the instrument panel.

Operation

The blower motor resistor is connected to the vehicle electrical system through a dedicated wire lead and connector of the HVAC wire 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 in the MTC HVAC system directs the ground path for the blower motor through the correct resistor wire to obtain the selected speed. With the blower motor control in the lowest speed position, the ground path for the blower motor is applied through all of the resistor wires. Each higher speed selected with the blower motor control applies the blower motor ground path through fewer of the resistor wires, increasing the blower motor speed.

The blower motor resistor cannot be adjusted or repaired and must be replaced if inoperative or damaged.