Why Is My Furnace Making a Squeaking Noise?

Furnaces create a background noise when in use, but sometimes they make sounds that have you questioning if it’s normal. Is your furnace squealing or squeaking loudly? Is it creating a noise you’ve never heard it make before? Is the noise noticeable enough that you’re starting to wonder if something is wrong?

This blog will outline some of the reasons why your furnace could be making such a horrible noise and what you can do to fix it.

Sometimes a high-pitched whistling or squealing can be due to poor airflow. Poor or low airflow usually comes from your blower struggling to push out air.

One of the reasons that your blower could be struggling includes a dirty air filter. A dirty air filter is when the thin netting has caught dust and debris that cycles through your home when your AC is on. When that happens, little bits of air can slip between pockets of debris and create that annoying whistling sound you’re hearing.

We suggest changing your air filter, especially if it’s dirty. Your air filter should be changed at least once every three months, and the sooner, the better if it has already collected a significant amount of dust and debris.

Another reason you may be hearing a strange sound is if your vents are closed or obstructed or if you have dirty or damaged ducts.

Closed vents can catch the hair in a way that could make air whistle or could obstruct airflow entirely. The vents could catch debris contributing to that strange noise. Dirty or damaged ducts can create a similar problem—air diverts, then creates a squeaking sound.

Try opening all the air vents to see if that fixes your problem. You can examine the inner workings of your ducts to some degree on your own. Still, you may need to contact a professional HVAC Service Technician to check deeper within the duct system if you believe that to be your problem.

Note: You should not attempt to fix or dislodge anything that could be obstructing your ductwork by yourself, or you will risk potentially damaging your system further.

However, there are other reasons your furnace could be making strange noises, too. We’ll explore more of those potentials below!

Depending on the age of your furnace, it could be a worn-out fan belt. A fan belt drives your furnace’s means of blowing warm air into your home.

If you feel comfortable, you can remove the cover of your blower compartment to examine the belt itself. If you do not see a belt when you remove this cover, you can skip to the next section.

If you see a belt, you should examine it for noticeable wear and tear signs, including cracks or malformation:

1. By pressing on the belt with a finger, you can test how tight around the pulley system it is. If you press on it and it gives more than ¾ of an inch of slack, it’s not tight enough for your system.
2. Using a wrench, you can tighten the pulley system yourself if you like. Only do this if there is no other visible sign of wear, as mentioned above.
3. You can push the motor back into the motor mount by loosening the two motor bolts, letting the fan belt pull taut and stay secure.
4. Remember to tighten the bolts again after you have reset the motor and tightened the fan belt.

If you don’t feel comfortable attempting to fix your motor and fan belt, you can always contact a professional for the job!

If you can’t immediately identify a fan belt, your furnace likely uses blower motor bearings. These bearings are little wheels that “bear” the brunt of the friction that comes from your furnace doing its job. They spin quickly to take away pressure from the rest of your system and can suffer the effects of wear and tear as a result.

With worn-down bearings, their spinning is likely causing that squealing sound. Whether they’ve come loose and begun to rattle or have gathered debris that’s grinding as they spin, it’s a high possibility this is where your issue lies.

Unfortunately, there’s little someone without proper training can do if the squeaking and squealing come from blower motor bearings. You will need to hire a professional HVAC Service Technician to come and look at your furnace for you if this turns out to be the case.