What can cause a blower motor to stop working?

In most cases, a blower motor resistor fails due to corrosion or overheating. Sometimes, the mechanical resistance to the motor rotation causes an excessive electric current that can overheat and prematurely damage the blower motor resistor.

What controls the blower motor speed?

Blower Motor Resistor Operation
The blower motor resistor is responsible for controlling the blower motor speed.

How do I control the fan speed on my blower?

You can increase or decrease the blower speed by slightly adjusting the pulley on the blower drive motor. To increase blower speed, slightly loosen the setscrew that holds the pulley to the driveshaft. Move or turn the pulley clockwise on the shaft one turn, then tighten setscrew.

What is the yellow wire on a blower motor?

Check the diagram on the old motor, to figure out which wires are which. From what I can see, looks like on the old motor: Black = High speed, Yellow = Medium high, Orange = Medium Low, Red = Low speed.

How do I know if my blower motor is bad?

If it’s good, refer to a wiring diagram for your vehicle and conduct these tests: Disconnect the electrical connector at the blower motor and jumper power and ground to the motor, bypassing all the speeds controls.

Do you need a blower motor resistor for a variable speed motor?

Or, carmakers can supply power to the motor and control blower speeds on the ground side of the circuit. See the wiring diagram for that setup below. Or, carmakers can opt for a motor resistor AND a high speed relay. See the wiring diagram below for that setup. Variable speed blower motors don’t use a blower motor resistor.

What does half speed driver mean on a blower motor?

So a half speed driver request will result in the blower motor controller pulsing the ground connection off twice as often as when the fan is running at full speed. Carmakers use these three common wiring methods to supply power and ground to the blower motor in a manual system using a blower motor resistor.

What causes a blower motor to stop working?

In a situation where the motor doesn’t work on any speed, the most likely causes are: a blown power supply fuse, a bad motor ground connection, bad motor speed control module or a failed motor. On all systems, a failed blower motor is least likely. Blower motors generally don’t fail out of the clear blue.