There are many parts of a vehicle that can go bad over time. Some are very easy to diagnose, but some are a bit harder than others. Here is what you need to know about a blower motor resistor to tell if it is bad and in need of replacement.

The Purpose Of The Blower Motor Resistor

The job of the blower motor resistor is to control the speed of the blower that pushes hot and cold air into your vehicle. This is done by restricting how much power is sent to the blower motor. Less power will result in the fan spinning slower, and more power causes it to spin faster. You can typically access this part from inside your vehicle, with it being located beneath the glove box on the passenger side of the car. While it is a small part, it plays an important role in how the blower motor operates. 

The Signs Of A Bad Blower Motor Resistor

There are a few signs that can indicate there is a problem with the blower motor resistor. One of the most common signs is that the blower motor only operates on the highest fan setting. If the resistor is unable to limit the power to the blower motor, the blower will simply operate at its highest speed because it is incapable of running at other speeds. Many people wrongfully assume this is a problem with the controls in your vehicle that send a signal to the blower motor, but it's actually the resistor. 

You may also have the opposite problem, where no air comes out of the vents in your vehicle at all. This is because it's possible for the resistor to not transmit any power to the motor at all, which causes it to not turn on at all. The motor may also be stuck on a single-speed, or only operate on some of the speeds on the control dial. 

The Other Potential Problems

The problem with diagnosing an issue with the blower motor resistor is that problems with the blower motor can be due to other problems. If you've replaced the blower motor resistor and the motor doesn't work right, consider taking your vehicle to a mechanic to figure out what is wrong. It could be due to a connector that has melted, a switch that has failed, the blower motor itself failing, a poor ground connection, or simply having a blown fuse.  

For more information, contact a local repair shop like Subie Repair Specialist.