9 Common Furnace Noises and What They Mean

Over time, when you fire up your furnace, you know how it’s supposed to sound. So it will likely catch your attention if the unit starts making strange sounds. Some noises — like several minor pops or clicks prior to the warm air beginning to blow — are completely harmless. But others could impair the equipment or even jeopardize your health if you dismiss them. Of all the furnace noises you might encounter, here are nine that justify an immediate furnace repair.

Scraping Furnace Noise

When you hear a sound like metal against metal, this could suggest the blower wheel has come loose from the motor shaft, or the wheel or motor mount has broken. No matter the exact problem, you should power down your furnace if you discover a scraping sound and call a professional for an emergency repair.

Loud Boom at Startup

When you fire up your furnace, the burners should ignite without delay and get started heating your home. A loud boom at startup potentially means the burners are dirty, resulting in delayed ignition. When the gas finally does ignite, you hear this scary furnace noise.

A small explosion each time your furnace turns on could crack the heat exchanger, a costly repair that may force you to remove and replace the entire furnace. Don’t let it come to this! Turn off your furnace if you hear a loud boom at startup, and avoid using it again until it has been repaired.

Squealing or Whining Sounds

A squealing furnace noise typically signifies poor lubrication. Multiple parts of a furnace need lightweight oil to operate smoothly. If these parts are dry, components grind against each other and cause unnecessary wear and tear. Our recommendation is to have this problem remedied right away to prevent premature furnace failure.

Chirping Noise

The sound of a bird lodged in your furnace definitely warrants investigation. If you hear chirping during the first furnace cycle of the season, it could just mean your furnace is warming up after an extended period of no use. In this situation, the sound should go away after a few cycles.

However, if the chirping doesn’t subside, it could mean the pulley for the blower motor is crooked or the mounting plate is coming in contact with the blower wheel. This isn’t necessarily a safety risk, but the only option to stop the pesky furnace noise is to have a technician conduct a repair.

Screeching Furnace

Screeching noises are definite indicators that the fan belt is failing. If the fraying belt splits, it could whip around inside the furnace, damaging other components and resulting in a much more expensive repair. Insulate yourself from this hassle by replacing the worn-out belt sooner rather than later.

Persistent Clicking.

Some furnaces give off a quick series of clicks when they flip on and off. There is nothing unusual about that. However, if the noise lasts longer than approximately 60 seconds, this could indicate an electrical complication. Don't risk an electrical fire! Simply call a furnace repair professional to fix the problem immediately.

Thwapping Sounds

The blower motor should perform without problems when the furnace switches on. If you discover a thwapping sound that dramatically picks up speed as the blower gets going, this likely means something is snagged in the fan, and the blades are smacking it with each rotation. A quick repair should be all that's required to get rid of this bothersome furnace noise and protect against damaging the blower motor.

Rattling Furnace

A few different problems can cause your furnace to rattle. It might be as easy as a loose door cover, so start there. If the rattling remains, the most probable reason is a declining blower motor. Treat this as a warning sign to have your furnace repaired before it entirely fails.

Whistling or Vibrating

When these noises come from the furnace, it could mean the air intake vent is dislodged. If the whistling or vibrating comes from a vent, your ductwork is likely separated somewhere, allowing conditioned air to release. These aren’t urgent matters, but if you address it promptly, you’ll pay less on your heating and cooling bills long term.

Schedule Furnace Repair with Service Experts Heating & Air Conditioning

Are you unsure whether the furnace noises you hear match these descriptions? Perhaps nothing is wrong, but if you want to be 100% sure, the easiest thing to do is to call a professional. At Service Experts Heating & Air Conditioning, we have emergency furnace repair to get your unit back up and running as quickly as possible. Be confident knowing that we stand behind our work with a one-year, 100% satisfaction guarantee. If you’re disappointed with our work anytime in the next 12 months, we’ll set things right! For more information or to arrange a furnace repair visit, please get in touch with a Service Experts office near you.