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


This site is reader-supported and we earn commissions if you purchase products from retailers after clicking on a link from our site. As an Amazon Associate, we earn from qualifying purchases.

After a long summer, switching the furnace on to heat up your home as winter arrives may lead to the presence of a few alarming noises. While some of these noises are okay if they are temporary, there are times where a sound from the furnace indicates something serious. If the furnace is making a chirping sound, you should understand how to get to the source. 

To fix a furnace making chirping sound, consider how long the device was turned off, look for problems with the fan belts, make sure the mounts used to secure the motors in place are fastened properly, and check if there are bearings that have been worn out. 

With the details we provide in this article, you can attempt to identify the reason for a chirping sound in your furnace. We also share fixes that help you realize what needs to be done. 

The Furnace Was Off During Summer Months

While a chirping sound, or any other noise, coming from the furnace feels like an alarm going off, there are certain times when they do not signal something serious. A furnace making chirping noise can sometimes be normal – but only in specific circumstances. 

Consider whether you have had the furnace off for some time before hearing the chirping noise. Most people tend to switch the furnace off in summer. This helps you save on your power bill, as heating happens naturally during these warmer months of the year. 

How To Fix

When the noise occurs after starting the furnace for the first time after a while, you should give it a bit of time. Let the furnace run for a few days and see if the problem goes away. Take note that it is not guaranteed that the problem is only temporary or just because the furnace was off for some time. There are a few more serious issues to keep in mind – so you should make sure to check up on the furnace frequently. 

If the chirping noise goes away after a few days, then you can relax. The problem was simply due to a build-up of some dirt when the device was turned off. When the chirping sound continues to be present after a few days, it is time for further investigation. 

Motor Mounts Are Loose

If you find that the furnace making chirping sound is not caused by the system being kept off during the summer months, then you should start looking inside. One of the first things you want to look at is the mounts that help the motors stay in place while operating. These mounts are fastened to the rest of the furnace using bolts or screws. 

When one of these screws or bolts come loose – even just a little bit – it can cause an unpleasant sound when the furnace is on. A few sounds may occur, depending on what mount is loose and how to lose it is. A chirping sound may occur if the screws are still in place but just not fastened properly. 

How To Fix

The fix is pretty much self-explanatory. When there are loose screws or bolts, the solution would be to fasten them. To do this, you first need to inspect the motors and the attached mounts. For this, you will be working inside the furnace, so that means switching the entire system off for safety reasons:

  1. You can get into the furnace by opening up the door in the main compartment. You may need to loosen some hardware to do this. 
  2. Take a look at all mounts that help to keep motors intact. This includes the blower motor and the inducer motor. A motor is found at the flue line, too – check this one as well. 
  3. Gently wiggle the mounts to see if any of them are loose. Use a wrench or screwdriver to tighten all the hardware used to fasten the mounts. 

Problems With the Fan Belts

Fan belts play a role in helping the motor drive rotations in the fans. These belts are used on all motor and fan assemblies in the furnace. The fan belts continue to run while you are using the furnace, so it is not uncommon for these parts to wear out over time. 

When fan belts wear out, they may become less efficient. There could be a reduction in the rotation of the fans. When this happens, less air may flow into the ducts. There may also be problems with the flue line, which creates a risk of combustion gases entering your home. 

If the fan belt wears out, it may create a consistent chirping sound during the entire time a furnace is on. As the belt continues to wear out, it may start to create additional sounds that are louder and more concerning.  

How To Fix

To determine if fan belt problems are causing the furnace to make a chirping sound, you need to inspect these components of the system visually:

  1. Open up the main compartment and find all the fan belts used in the system. Fan belts can be found in all areas where a motor and fan are used in the furnace. 
  2. Look for visible signs of damage on the fan belt. This may include tears, for example. 
  3. Take note of a fan belt that has become too thin. These belts tend to thin out over time. 

If there are worn out or damaged fan belts, they need to be replaced. 

Here’s a video that shows you how fan belts in the furnace are replaced:

Worn Out Bearings

Wear does not only occur to fan belts that are installed in your furnace. The bearings used to assist with the rotating action of the fans can also wear out. As these bearings wear out, you may find that they start to produce a noise. A chirping sound may happen at first – which means you should consider this particular noise an early sign of a developing problem. 

As the bearings wear out more, they can become damaged. When the metal parts are exposed at the center, the bearings can cause damaged parts of the motor assembly. This can create more of a squealing sound – which happens when there is more significant damage. 

How To Fix

Replacing bearings is the only effective solution when these components are worn out. By visually inspecting the bearings inside the furnace, you will determine if they might be the cause behind a chirping sound:

  1. When opening the furnace, make sure the power source is turned off. 
  2. Check all bearings. There are multiple bearings in each of the motor assemblies used in the furnace. 
  3. Look for signs of damage and wear. See if you can find cracks in the bearings, as this is another indication of damage. 

Replace any bearings that you find has experienced too much wear. Damaged bearings should also be replaced. 

Summary

Chirping from the furnace may be annoying but can sometimes be just a temporary problem when the device is turned on after being off for a long time. There are also times when a chirping sound may signal loose parts or an issue with fan belts or bearings, which need to be addressed. 

A specialist who is appropriately qualified can help to detect the source of a furnace making chirping noise without any delay. They can also offer you the right fixes to avoid future troubles. Using the form below, we can help match you to a local expert. 

Alanna Greene

Alanna is an avid traveler who lives in Michigan. In addition to writing for Temperature Master, she also sells crafts on Etsy and takes long walks through the forests near her home.

Recent Posts