Sounds That Tell You It's Time For A New Furnace

Is your furnace making noises that are making you nervous?

Here's a furnace sounds checklist to help you to know when to call your furnace service technician to check for furnace problems and possibly consider a new, more energy efficient furnace.

Grinding (metal scraping sound)

When you would describe your furnace sound as grinding, shut it off and call for service. Usually, the grinding sound is a belt issue that can cause more serious problems if left running, or there is a major problem with the blower wheel or blower mount.

Screeching or squealing

These noises can indicate a serious problem with the motor, and these furnace problems require a service call, as it could be the bearing in your furnace motor. Alternatively, when you hear a loud squeal it could be that the belt that connects with the motor with the fan is slipping or frayed, the shaft bearings need maintenance, or that your blower motor is failing.


If your furnace is vibrating, there may be something unbalanced in your blower that is causing the vibration when the fan spins. A professional furnace service technician should be called to investigate such concerns.


A rattling noise from your furnace could be as simple as panels that have become a bit loose, allowing them to rattle as the blower fan turns and the air circulates. If, however, the rattle is happening before the blower turns on, it could be a more serious issue with your heat exchanger. Be sure to call a professional to check for heat exchanger damage, as this can lead to dangerous carbon monoxide leaks.


Usually, a chirping noise that sounds metallic is just the normal sound of your furnace. However, it can also signal a number of different problems with the furnace such as the blower wheel could be out of alignment or the mounting plate could be too close to the blower wheel.


A humming sound can be caused by one of several issues in your furnace, from the blower motor to the capacitor. It's best to call a qualified furnace repair technician to ensure an accurate assessment and safe repair.


When you can hear a constant clunking or bumping sound, it could be a cracked or defective belt that should be checked by a technician.


Clicking noises in your furnace can indicate that the bearings in your motor are getting older, and it is best to have these checked and replaced when necessary as this can save you from having to replace the motor if it burns out.

Crackling or buzzing

Buzzing sounds are often related to the electronic aspects of your furnace, such as the transformer box or blower motor, as well as the capacitor. As long as the furnace is turned on, power will be supplied to these elements, causing them to buzz.

Pinging or popping

Many furnaces, even newer models with much improved sound reduction, can make a pinging or popping sound. Usually, though, these sounds are coming from the air ducts. If you've had your air ducts cleaned and you can still hear the sound have your technician check it out during your annual maintenance checkup, it could be the result of a dirty furnace.


A big, loud boom sound is likely coming from contracting or expanding air ducts, not the furnace. If you can determine that the sound is not in the air ducts, then call for service because it could be a problem with a part, such as your gas valves.

Make the call to your experienced service technician to diagnose and repair furnace problems like unusual sounds to determine if the problem can be repaired, or if you need a new furnace.

Mr. Furnace can assess your furnace and help you decide if you need repairs or a new furnace. Schedule a maintenance appointment today.