Blower Motor Resistor: Description and Operation

Fig.9 Blower Motor Resistor:

FRONT BLOWER MOTOR RESISTOR
A blower motor resistor is used on this model when it is equipped with the manual heater-A/C control. Models equipped with the optional Automatic Temperature Control (ATC) use a blower power module, instead of the blower motor resistor. The blower motor resistor is installed in a mounting hole in the heater/AC housing, directly behind the glove box opening of the instrument panel. The resistor consists of a molded plastic mounting plate with two integral connector receptacles. Concealed behind the mounting plate within the heater/AC housing are four coiled resistor wires contained within a protective stamped steel cage. The resistor mounting plate is secured with two screws to the heater/AC housing and is accessed for service by rolling down the glove box from the instrument panel.

The blower motor resistor wires will get hot when in use. Do not touch the resistor wires or the protective cage if the blower motor has been running. The blower motor resistor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The blower motor resistor is connected to the vehicle electrical system through a dedicated take out and connector of the instrument panel wire harness. A second connector receptacle receives the pigtail wire connector from the blower motor. 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 manual heater-A/C control 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 blower motor switch is in the highest speed position, the blower motor resistor wires are bypassed and the blower motor receives a direct path to ground through the blower motor switch. The blower motor resistor may be diagnosed using conventional diagnostic tools and methods.

Fig.8 Blower Motor Resistor:

REAR BLOWER MOTOR RESISTOR
A blower motor resistor is used on this model when it is equipped with the manual heater-A/C control. Models equipped with the optional Automatic Temperature Control (ATC) use a blower power module, instead of the blower motor resistor. The blower motor resistor is installed in a mounting hole on the back of the rear heater-A/C unit housing, directly above the expansion valve. The resistor consists of a molded plastic mounting plate with an integral connector receptacle. Concealed behind the mounting plate within the rear heater-A/C unit housing are two coiled resistor wires contained within a protective stamped steel cage. The resistor mounting plate is secured with two screws to the rear heater- A/C unit housing and is accessed for service by removing the right quarter and D-pillar trim panels.

The blower motor resistor wires will get hot when in use. Do not touch the resistor wires or the protective cage if the blower motor has been running. The blower motor resistor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The blower motor resistor is connected to the vehicle electrical system through a dedicated take out and connector of the rear HVAC wire harness. The blower motor resistor has two 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 manual heater-A/C control 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 both 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 blower motor switch is in the highest speed position, the blower motor resistor wires are bypassed and the blower motor receives a direct path to ground through the blower motor switch. The blower motor resistor may be diagnosed using conventional diagnostic tools and methods.