3 Signs of a Bad Blower Motor Resistor (& Replacement Cost)

The blower motor resistor ensures your blower motor fan is not going at full speed all the time. Here's how to tell your blower motor resistor is bad

blower motor resistor

When you sit behind the wheel of your vehicle, you expect the climate controls to work as directed. So, what happens when the system isn’t blowing air as you demand? In some cases, it could be a bad heater blower motor resistor causing your trouble.

In this article, we discuss the symptoms that the blower motor resistor is failing and show you where to look for it. We also discuss the replacement cost, so you can determine if it is worth fixing. Let’s begin with a look at the signs to look for:

The most common symptom of a bad blower motor resistor is the blower motor will only work at one or two speeds. It can also cause the blower motor to stop working completely and you will notice no air coming from the vents.

Here’s a more detailed list of the most common symptoms of a bad blower motor resistor:

Bad Blower Motor Resistor Symptoms

1. Only One Speed From Blower Motor

air condition controls

One of the most common symptoms of trouble with the blower motor resistor is when the fan gets stuck in one setting. Because the blower motor resistor adjusts the fan speed, the inability to change it can point to problems.

If the resistor fails or shorts, the blower motor might remain stuck at a particular speed. While you could still use the air conditioning or heater at his speed, you will want to repair it for complete functionality again. 

This symptom can also be caused by other bad HVAC parts. You might want to troubleshoot the connections to the motor or the fan switch to ensure they haven’t become faulty. 

2. Various Airflow Settings Not Working

air vents car

On the other hand, you might notice that the fan works in several settings, but not all of them. When the system is off, the blower motor resistor isn’t needed. This is also true when the blower motor is set for full speed. 

However, the other settings require the resistor to control the flow. With that said, this condition could also be caused by the blower motor switch. Because of this, you might require a further diagnosis to determine which part is the culprit. 

3. No Air Coming From Vents

When the resistor goes out, you might not be able to get any air to come out of the vents. The blower motor resistor controls the power to the system’s blower motor. When it fails, it can cut off all power to the motor.

When the blower motor doesn’t get power, air pressure can’t be produced. You are left with a heater or air conditioner with nothing coming out of the vents. 

However, there are other things you might want to check before the resistor if nothing is coming out of the vents. If nothing is working, you should start by looking at the fuses first. From here, you might also consider that the blower motor itself has quit. 

The Function Blower Fan Resistor

blower fan resistors

The blower motor resistor is part of the HVAC system and is an electrical component. It controls the blower motor fan speed. When you adjust the fan speed on the instrument cluster in your vehicle, the resistor is responsible for adjusting the speed that the blower motor runs at.

Because the fan speed is regularly adjusted, the resistor endures a lot of wear. The constant stress can cause it to fail at any time. 

Heater Blower Motor Resistor Location

The heater blower motor resistor is often found beneath the dashboard. It is located in the heater and air conditioning compartment. It’s connected to the air conditioning system, where it can adjust the speed of the blower motor fan. It can also be found behind the glove box of some vehicles. Either way, you will find it close to the blower motor.

When the resistor fails, it becomes more difficult or impossible to change the airflow speed. To diagnose it, the electrical circuits must be evaluated. There are many parts that could cause the same problems, but they are all located relatively close to one another for easier diagnosis. 

Heater Blower Motor Resistor Replacement Cost

The heater blower motor resistor replacement cost could be between $10 and $60, depending on what type of car you drive. In the scheme of air conditioning and heater parts, this is one of the least expensive to replace. 

The heater blower motor resistor can often go bad because of a bad heater fan, and therefore you often have to replace both the heater blower resistor and the fan.

It’s also not a difficult part to replace. It might take you more time to diagnose the problem versus replacing the resistor. If you aren’t comfortable replacing the resistor on your own, you will need to have a professional mechanic tackle the job.

The average labor costs to replace a blower motor resistor vary based on where you live and the type of vehicle you drive. It’s wise to shop around because you could get a variety of quotes, with some being nearly double another provider. In general, you can expect to pay between $50 and $200 for the labor associated with blower motor resistor replacement, giving you a grand total of between $60 and $260 for parts and labor.

Written by:

Magnus is the owner and main author of MechanicBase. He has been working as a mechanic for over 10 years, and the majority of them specialized in advanced diagnostics and troubleshooting. He has also been a motorsport (drifting) driver for over 5 years.