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Atlantic Refrigeration and Air Conditioning, Inc. Blog

How Worried Should Those Furnace Noises Make You?


When your furnace is running during cold weather, you have a good idea of what kind of noises it makes. A modern furnace won’t make a racket, but it does create a blanket white noise of air moving through the vents. When you’re near to the HVAC cabinet, you’ll be able to hear the burners running and the noise of the blower fan and its motor.

But if your furnace is making unusual sounds, ones you aren’t accustomed to hearing, you may feel worried something is wrong. Is it an emergency that needs 24/7 services from a Smyrna, DE, HVAC contractor? Or is it maybe nothing and you’re overreacting?

Before we explore some of the possibilities below, we want to reassure your that you’re never overreacting when it comes to concerns about a furnace. It may end up as small issue, but you’ll still be thankful you called for professional to make sure of it.

Banging and clanging from the vents

A sound like metal warping isn’t uncommon in HVAC systems, since it’s often the sound of metal ductwork enlarging and contracting as heat passes through it. However, this may also indicate the ductwork has damage and needs duct testing and sealing. If the sound is more mechanical, you may have a problem with a bent blower fan blade or a loose part. Check with the sound from the cabinet. You’ll probably need to call for repairs for this.

Shrieking and grinding

These are more extreme mechanical noises, and they are a good reason to feel concerned. Shrieking is a warning that the bearings in one or more of the motors is wearing down. Bearings can be replaced, and they need to be before wearing down completely and causing permanent damage to the motor. A grinding sound is likely a motor that’s already burning out—you may notice an acrid smell as well. Call for emergency repairs to fix this.

Rattling cabinet

This might be a simple problem: the cabinet door is loose. Shut and latch it again to see if it fixes the problem. If it doesn’t, the cabinet itself may be loose or the rubber on its feet has worn down.


An abrupt “whoosh!” noise from the furnace during its start-up cycle means the burners are having a delayed ignition for some reason. Gas is entering the combustion chamber and building up before it ignites, and the large amount of gas all ignites at once in a large noise. You’ll need to have repair technicians find out what’s preventing standard burner ignition, and they may need to clean the burners.


If the furnace clicks as it tries to turn on, it probably means the electronic ignition system is dying and will need technicians to replace it. If the clicking sound comes after the blower fan turns off, this is a major concern because it may mean a cracked heat exchanger—and that’s a health hazard for your home! Shut off the furnace and gas to the furnace, then call for emergency repairs.

Keep in mind that you can’t perform furnace repairs on your own. When in doubt, always call on the licensed pros.

“We Take Pride in Your Comfort” at Atlantic Refrigeration & Air Conditioning, Inc. Call us 24/7 for emergency furnace repair service.

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