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Furnace Making Squealing Noise? 4 Common Causes (+ Fixes)

Even though your furnace is made to last you decades, several smaller parts wear out over time and need replacing. These smaller issues can develop into serious complications when not addressed. A furnace making a squealing noise is often a sign of a small problem that you can fix easily.

Your furnace is making a squealing noise because the bearings are worn out, the blower isn’t aligned, the blower belt is worn out, or the blower motor is faulty. Easy fixes include inspecting and replacing the damaged parts, aligning the blower, and calling a technician to inspect your furnace.

This article will educate you about the most common reasons why your furnace is making squealing noises. In most cases, the fix is rather simple, so you can do it yourself. However, taking action on time is crucial as these problems can quickly turn into an expensive repair down the line. 

Worn-Out Bearings

One of the first things you want to look at when the furnace makes a squealing noise is the blower fan and motor bearings. These bearings take a lot of stress over the years, so they wear out with time. 

Worn-out bearings mean metal is rubbing against metal, resulting in a loud squealing noise. The noise may be subtle in the beginning, but it gradually becomes louder and more distinctive.

Taking appropriate action is vital as worn-out bearings can cause problems in the future. If your furnace keeps running on worn-out bearings, they’ll damage the blower motor and related parts. 

How To Fix

If you think the squealing noise is coming from the bearings, turn off the furnace and investigate. The goal here is not only to fix the problem but also to prevent further damage. Here’s how to check:

  1. Turn the furnace off. 
  2. Open up the main panel. Get a screwdriver to loosen the screws that hold the panel in place. 
  3. Locate the blower. When you find the blower, take a closer look at the bearing. 
  4. Look for signs of wear or corrosion.
  5. Replace the bearing if necessary.

If you need to replace the bearing, take a look at the video below:

The Blower Isn’t Properly Aligned

The blower consists of multiple parts, including a motor and a fan, among others. These parts need to be connected to each other while also being in perfect alignment. If one part of the blower goes out of proper alignment, it can cause multiple issues with your furnace. 

This can be a tricky situation. It’s difficult to determine whether a part is misaligned if you’re not an expert. Moreover, we don’t even know if this is the cause behind the squealing noise. If you do determine that the problem lies with the blower, it’s still hard to determine which part is the one that has become misaligned. 

Refer to the manual or the technical documentation for your furnace if you still have it. There should be a diagram that shows where each part of the furnace is located. You can use this as a reference to ensure everything is aligned and installed correctly. 

How To Fix

Opening up the furnace is the first step. Similar to the previous solution, you need to find your way to the blower:

  1. Turn off the furnace.
  2. Remove the panel.
  3. Locate the blower and carefully inspect every part that connects. 
  4. Check where the parts are connected and tighten any loosened screws or bolts. 

If you find a part that isn’t properly aligned, you need to follow the appropriate steps to fix the misalignment. You might have to loosen some parts first and then push the hardware into the appropriate positions before fastening the screws and bolts. When in doubt, contact a technician.

The Blower Belt Is Worn Out

A belt is used to drive the fan that helps distribute warm air. This belt moves continuously to ensure the motor’s action allows the fan to rotate at an efficient speed. Consider the speed at which the fan’s blades turn. The belt needs to move fast enough to support the blades.

The belt wears out with years of use, affecting several functions of the furnace and the blower module. The fan may not turn as effectively as it used to when the blower belt wears out. If the belt breaks, the fan can no longer rotate.

In terms of the furnace making a squealing noise, a worn-out blower belt can cause friction and make a squealing sound as it turns. 

How To Fix

First, determine if the blower belt is to blame for the noise. Note that a replacement is inevitable if the problem lies with the belt. There is no use in trying to fix the blower belt.

Here’s how to examine the blower belt:

  1. Make sure the furnace isn’t on.
  2. Open up the panel on its casing. 
  3. Find the belt and take a look at it. You may need to use a flashlight to see it clearly. Look for signs of thinning, chips, and other types of damage.
  4. See if you can pull gently on the belt to get it to move a bit. If it’s not moving at all, the belt needs to be replaced. 

This video shows you how to replace a fan belt on the blower:

The Blower Motor is Faulty

Like the other parts of the furnace, the blower motor wears out over time, especially with frequent and consistent use. A faulty blower motor won’t function as efficiently as it should, resulting in poor heat distribution to your rooms. 

A faulty blower motor may also cause a squealing sound, which sometimes indicates metal parts rubbing against one another as the motor operates. 

When the motor causes the squealing sound, it doesn’t necessarily mean that the motor is broken. Note that the motor is typically adjusted following the installation process. Problems can occur with the adjustments of the motor, resulting in a squealing sound. 

How To Fix

You first want to check if the motor is adjusted. The adjustment depends on the motor in question. It should comply with the rest of the system. 

If you’ve determined that the adjustment is incorrect, you need to get the blower motor repaired or replaced. 

Here’s a video that explains how a blower motor is replaced and adjusted:

Summary

Problems with the blower can result in a furnace making a squealing noise. This is often considered a sign of worn-out and damaged parts that can worsen with time.

A squealing sound coming from the furnace means you need to check the internal parts. This calls for a professional who can work on a furnace.

Author

  • Chris Hewitt

    Chris is a Texas-based freelance writer who loves the outdoors and working in his garage. When he's not enjoying the Texas sun, he can be found tinkering with all sorts of things in his workshop.

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