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Why Is My Furnace Blower Fan Squeaking?

Is the squeaky, dying bird noises coming from your furnace blower fan wearing your patience thin? Are you ready for it to disappear forever?

Well, the first step is finding the source of the noise. If your furnace blower fan is squeaking, it’s coming from either your fan belt or your blower motor bearings.

Let’s take a closer look at some of the specific problems you may be having and what you can do to fix it.

If you don’t care what is causing the noise and just want the squeaking fixed now, please contact a professional to find and solve the problem.

If you would like to get an idea of what might be causing the problem on your own, we have some steps for you to take to help deduce what the problem might be. If you are going to go this route, please turn the power to your system off before you do anything else.

First off, is your blower fan belt-driven or direct drive?

Diagram of belt-driven furnace blower

Image source.

To start, you should know that unless your system is super old or a commercial system, it is highly unlikely that your system is belt-driven… but you never know! Moving on…

If you feel comfortable, remove the cover of your furnace blower compartment. Do you see a belt attached to the blower? If so, you have a “belt-drive” blower. If not, you have a “direct drive” blower.

So, why is this important? Well, if you have a belt-driven blower fan, you’ll need to inspect your belt for signs that it’s causing the squeaking noise.

If you have a direct-drive blower fan, you’ll want to skip to the section on blower fan motor bearings.

It could be a loose or worn-out fan belt

Belt-driven furnace blower fan

Belt-driven furnace blower motor.

If you have a belt-driven blower fan, a loose belt can cause squeaking noises. If your fan belt isn’t tight enough, it can also slip off its pulley track and cause the fan to stop working properly. Then, voila, you’re not getting as much heat as you’re paying for.

So, let’s make sure this isn’t the case in your situation (and fix it if it is).

To check your fan belt for too much slack, follow these steps:

  1. Remove your furnace blower compartment cover.
  2. Visually inspect the fan belt for cracks or signs of wearing. If you see these issues, you’ll need a professional to replace the belt. If the belt is in good shape, continue on to the next step.
  3. Using one finger, press lightly against the fan belt. The fan belt should be tight enough to keep it from slipping off its pulley. If it deflects more than ¾ of an inch when you press against it, it’s most likely too loose.
  4. To tighten the belt, you need to position the motor farther back into the motor mount. This keeps the belt taut. To do that, find the two adjusting bolts on either side of the motor (see figure above).
  5. Loosen both bolts with a wrench until the motor is loose and can be moved back and forth.
  6. Push the motor backwards into the motor mount until you have proper tension in the fan belt. Then, tighten the two adjusting nuts.

Not up for this DIY repair? No worries, a professional can handle this in less than 10 minutes.

Not your fan belt? Then, it could be worn-out motor bearings

Your motor bearings are small wheel-shaped devices that “bear” the brunt of the friction as your blower motor spins. So, it’s safe to say that bearings often wear out and need to be replaced.

Unfortunately, you’ll need a professional to replace the bearings because it requires taking apart the blower motor.

Need help from an AZ tech?

If you’re not sure what’s causing that incessant squeaking noise, we’re here to help. Just contact us with your problem and we’ll send a tech over as soon as possible to fix it.