Symptoms of a Faulty or Faulty Heater Fan Motor Resistor

Common signs include the car's heater not working or stuck at a certain speed, or something is stuck in the fan motor.

The blower motor resistor is an electrical component that is part of the vehicle's heating and air conditioning system. It is responsible for controlling the fan speed of the fan motor. When the fan speed is changed using the knob on the instrument cluster, the fan motor resistor changes setting, which causes the fan motor speed to change. Because fan speed is one of the most frequently adjusted settings in an air conditioning system, the fan motor resistor is subjected to constant stress, which can eventually lead to failure. A defective fan motor resistor can cause problems with the operation of the entire heating and air conditioning system. Usually, a bad or faulty fan motor resistor causes several symptoms that may alert the driver to a potential problem.

1. Fan motor stuck at one speed

A common symptom of a bad fan motor resistor is the fan motor stuck at one setting. The fan motor resistor is the component directly responsible for controlling the fan speed of the fan motor. If the resistor shorts out or fails, it can cause the fan motor to get stuck at one fan speed. Heating and air conditioning systems may still operate at the same speed, but the resistor will need to be replaced to restore full functionality.

2. The fan motor does not work under certain settings.

Another common sign of a bad fan motor resistor is a fan motor not working at certain settings. If the internal components of the fan motor resistors fail, it can cause the fan motor to malfunction or not work at all at one or more settings. This can also be caused by the fan motor switch, so it's highly recommended that you run a proper diagnosis if you're not sure what the problem might be.

3. No air from car vents

Another sign of a bad blower motor resistor is the lack of air from the car's air vents. The power to the fan motor is supplied through the fan motor resistor, so if it fails or there is any problem, the power to the motor can be cut off. An unpowered fan motor will not be able to generate air pressure, leaving the heating and air conditioning system without air coming from the vents.

Since the fan motor resistor is the component directly responsible for powering the fan motor, if it fails, serious problems can occur with the fan motor and the heating and air conditioning system. If your vehicle exhibits any of the above symptoms, or you suspect that there may be a problem with the blower motor resistor, have a professional technician, such as AvtoTachki, have the vehicle inspected to determine if the component should be replaced.