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3 Signs of a Bad Blower Motor Resistor

3 Signs of a Bad Blower Motor Resistor
10 August, 2022

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:

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 blog, we discuss the signs that the blower motor resistor is failing and show you where to look for it. Let’s begin with a look at the signs to look for.


The most common symptom of a bad blower motor resistor is that you will only notice that your blower is working on the highest speed setting or that it won’t work at all.

The main symptoms of a bad blower motor resistor include:

  • Only One Speed From Blower Motor
  • Various Airflow Settings Not Working
  • No Air Coming From Vents

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


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.


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.


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 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.



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