4 Symptoms of a Bad Blower Motor – Here’s What to Check

It should be pretty easy to tell when you have a bad blower motor. Just feel around your vents to see if there is any air coming out, right?

The truth is that it’s not always that simple. You also need to find the reason why the blower motor went bad in the first place.

If you don’t address the root cause of a bad blower motor, your next one will go bad too.

In this article, I’ll go over the symptoms of a bad blower motor. I’ll also outline what your next steps should be if you have a bad blower motor.

What are the symptoms of a bad blower motor?

If you’re trying to figure out if you have a bad blower motor, it’s important to know what to look for.

Here are 4 common symptoms of a bad blower motor:

  1. Low/no airflow from vents. The classic sign of a bad blower motor is restricted airflow coming from your air vents. If the blower motor is completely bad, then you’ll have no airflow at all.
  2. Strange sounds coming from blower. Blower motors can make all kinds of sounds, depending on what the issue is. Vibrations, grinding, and high pitched-noises are some of the sounds a blower can make if it’s going bad.
  3. Circuit breaker keeps tripping. A blower motor that’s seized up is bound to trip a circuit breaker. (A bad capacitor will trip the circuit breaker too, so be sure to check that first.)
  4. Hot/burning smell coming from air vents. A bad blower motor will sometimes overheat, causing a “hot” smell to come out of your air vents. In the worst scenarios, your blower motor may actually start to burn. Yikes!

What causes a bad blower motor?

Blower motors go bad due to one of a few reasons:

  • Overheating from airflow restriction
  • Bad bearings
  • Damaged fan blade/scraping sides
  • Damage in motor windings
  • Rust in the motor’s internal components

Depending on the reason your blower motor went bad, there may be additional work required besides just swapping out the blower motor.

For example, if your blower motor overheated due to airflow restriction, you’ll need to find the cause of the airflow restriction. Or else your next blower motor will go bad just as quickly.

Another reason why a blower motor might go bad is due to rust in the motor’s internal components.

Rust in a blower motor is a symptom of a dirty blower motor. This is why it’s important to change your air filters regularly and make sure that there are no air leaks in your furnace.

What to do if you think your blower motor is bad

If you think you have a bad blower motor, you should check a few things first. There’s a good chance that something else is causing the issue, and your blower motor is fine.

Here’s what to check first:

  1. Inspect your air filters. Lots of times, airflow restriction from a dirty filter will cause a blower motor to overheat. The excess heat in the motor will cause its performance to degrade, and the motor may fail altogether.
  2. If your blower has a fan belt, take a loot at it. If the belt is snapped, then the blower won’t work. Replacing the belt is a fairly simple fix.
  3. Another thing to check is the capacitor. The capacitor is used to start the fan so it’s worth checking if your blower motor won’t start up.
furnace blower motor capacitor

Check out this video from AC Service Tech that shows you how to check a blower motor’s capacitor and windings:

If the filters, belt, and capacitor look good, the next thing to do is to check out the blower motor itself:

  1. Turn off the power to your furnace and remove the cover from the blower compartment. Inspect the blower motor and look for any damage. Give the blower fan a spin with your hand to see if there is any scraping or wobbles.
  2. Bad bearings are another reason why a blower motor might be bad. The bearings are the part that allows the motor shaft to spin freely. If you have bad bearings, then your motor will resist turning.
  3. Damaged motor windings are a little trickier to find. The windings are encased inside the motor, so you won’t be able to see a damaged one. But you’ll be able to tell if you have one when the motor doesn’t run when everything else looks good.
  4. Rust formation inside the motor is another reason a blow motor may fail. Rust will cause a motor to seize up and prevent the motor from spinning.

If your blower motor has bad bearings, damaged windings, or is otherwise seized up, then you’ll need to replace the motor.

Replacing a blower motor is a decently challenging task, so most times it’s worth it to get an HVAC professional to do it for you.

If you’re up to the challenge, the best blower motor replacement video I’ve found is this one from Word of Advice TV. Check it out below:

Hi, my name is Trey Lewis and I’m the founder and chief editor at HVAC Training Shop. My goal for this website is to help homeowners troubleshoot and maintain their home’s HVAC systems. Whether it’s changing an air filter, troubleshooting a blower motor, or just buying a new humidifier, I want to make sure that you’re covered.

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