Expert mechanic explains why your car’s blower motor is crucial for proper AC and heating, how it works, and what to do if it fails.

Dear Mike,

I’ve been having some issues with the ventilation system in my car and I suspect it might be related to the blower motor. I’ve heard that this component plays a crucial role in keeping the AC and heating systems functioning properly. Can you shed some light on how the blower motor works and what kind of issues can arise when it fails?

Thanks in advance for your help!



Dear Naima,

Thanks for reaching out with your question about the blower motor. You’re absolutely right that this component is an integral part of your vehicle’s climate control system. Without a functioning blower motor, even the strongest AC or heating system in the world won’t be able to do its job properly. So, let’s dive in and explore how the blower motor works, and what kind of issues can arise when it fails.

The blower motor is the fan responsible for pushing heated or cooled air through the dashboard vents, based on the climate system settings and fan speed selected. When you adjust the fan speed, it sends a signal through a resistor to the blower motor to either pick up the pace or slow down. However, if your cabin air filter is blocked due to sediment and debris, the blower motor has to work much harder to pull outside air through the filter, causing it to get hotter and inevitably leading to failure of the bearings inside the motor.

But wait, there’s more! Before pointing the finger directly at the blower motor, it’s worth checking the fuses for the motor to ensure they’re still in good shape. Many vehicles have two fuses for the blower motor—one in the interior fuse block and the other under the hood. The blower motor is usually located under the dashboard on the passenger side.

When a blower motor fails, only a small amount of air will come through the interior vents as per the amount of outside air entering the climate system. Additionally, blower motors that make loud squeaks or rattling noises may be worn out and on the verge of packing it in. But don’t panic—sometimes those noises are caused by leaves or other debris that can be cleaned out after the motor is removed from the vehicle.

Another issue arises when it’s time to remove the cabin filter for replacement, as in most applications, the cabin filter sits on top of the blower motor assembly. If the filter is full of debris, it’s very easy to allow the debris to fall into the blower motor wheel cage. Once the blower motor is turned on, the cage acts like a blender and physically damages the cage.

So, what can you do if you suspect issues with your blower motor? First, check the cabin air filter and make sure it’s not blocked by debris. It’s something we recommend having a professional take a look into.

A good mechanic would look closely at the motor’s fuses and replace any that are blown. They should also check the voltage running to the motor and ensure the fan speed switch is functioning properly. Finally, they should remove the blower motor from the vehicle and clean any debris from the wheel cage.

The takeaway here is that if you’re experiencing issues with your vehicle’s heating or AC system, the problem may lie in the blower motor. But fear not, with regular maintenance and a little bit of TLC, your blower motor should keep on spinning just fine.

Please do not hesitate to hit me up with any other questions or advice in the future!


Mike Urban