That Sounded Expensive: How to Diagnose Scary Furnace Motor Sounds

furnace filter

There’s nothing worse than a broken heater in the middle of winter. Just the idea of such a thing makes a start shivering. 

Has your furnace motor been making some frightening noises? Has it turned into an energy vampire that’s causing your energy bills to skyrocket?

If you’re having problems with your furnace, keep reading.

Listed below are some common furnace sounds, along with information on what causes them and how you can help your system to run more efficiently.

Popping or Banging

When many people complain of a loud furnace, what they hear is a popping or banging sound when the furnace starts up or turns. This is definitely not normal.

If you have a gas or oil furnace, a popping or banging sound could indicate that the burner has a hard time reaching a temperature high enough for the fuel to combust.

This, in turn, causes fuel to build up. As a result, the excess gas or oil pops when the burner finally does reach a high enough temperature.


A rattling or rumbling sound is often indicative of a loose or damaged part. Common causes of rattling and rumbling include:

  • Loose debris in the unit
  • A broken fan blade
  • A problem with the motor
  • Loose ductwork

In order to find out what the cause of the rattling is, you’ll most likely need an HVAC technician to come in and take a close look at the system.

Dry Squealing

If you hear a dry squealing noise when your furnace is running, this could be a sign that the belts or bearings need lubrication. They may also need to be replaced altogether.

Unless you have a lot of experience when it comes to fixing furnaces, it’s best to call an HVAC technician to come in an lubricate or replace the bearings or belts.

This is a pretty laborious job. In addition to the actual replacement or lubrication, the technician will also clean and tune-up the furnace to make sure everything else is working properly.


Clicking is extremely annoying. But, it’s also often indicative of a more serious issue.

A clicking sound often comes from the heat exchanger or the furnace’s ignition. If you hear clicking, an HVAC technician ought to come in and take a look at the system.

If there’s nothing wrong with the heat exchanger or ignition, the technician will likely be able to get rid of the clicking by giving the system a simple tune-up.


If you hear whistling coming from your furnace, a clog in the air filter or air intake is likely the cause. The air filter or air intake could also be dislodged. 

A whistling sound coming from your vents could also indicate loose ductwork.

Be sure to have your airflow system inspected to make sure air is flowing efficiently through the ducts and not escaping.

Leaky ducts don’t just lead to an irritating noise. They’re also bad for your energy bills.

Is Your Furnace Motor Broken?

Now that you have this helpful information at your fingertips, have you diagnosed the cause of the sounds your furnace motor is making?

If your furnace motor is broken or worn out, it’s important to get it taken care of as soon as possible.

Need help figuring out how to fix your furnace motor? Need help saving up the money to pay to have it repaired?

Either way, check out the house and home section of our site today. There are tons of great resources here to help you keep your house warm and cozy all winter long.

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