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 you might be caught off guard if the unit starts making unfamiliar sounds. Some noises — like several small pops or clicks ahead of the warm air beginning to blow — are normal and harmless. But others could damage the equipment or even endanger your health if you neglect them. Of all the furnace noises you might encounter, here are nine that justify an immediate furnace repair.

Scraping Furnace Noise

The moment you hear a sound like metal rubbing on metal, this could mean the blower wheel has come loose from the motor shaft, or the wheel or motor mount is broke. No matter what the exact problem, you should shut off your furnace if you hear a scraping sound and call a professional for an urgent repair.

Loud Boom at Startup

When you start your furnace, the burners should ignite without delay and start heating your home. A loud boom at startup likely means the burners are dirty, producing a delayed ignition. When the gas eventually does ignite, you hear this shocking furnace noise.

A small explosion each time your furnace turns on could break the heat exchanger, a costly repair that may force you to replace the entire furnace. Don't wait to act when you hear a noise like that! Turn off your furnace if you hear a loud boom at startup, and don’t use it again until it has been repaired.

Squealing or Whining Sounds

A high-pitched squealing furnace noise usually implies poor lubrication. Shaft bearings and other moving parts require lightweight oil to run smoothly. If these parts are dry, components grind against each other and cause needless wear and tear. We suggest getting this situation remedied right away to protect against premature furnace failure.

Chirping Noise

The sound of a bird entrapped in your furnace definitely warrants investigation. If you perceive chirping when you fire up the furnace for the first time of the season, it could just mean your furnace is warming up after months of no use. In this case, the sound should dissipate after a few cycles.

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

Screeching Furnace

Screeching noises are an unmistakable warning sign that the fan belt is failing. If the fraying belt breaks, it could spin inside the furnace, harming other components and contributing to a much more expensive repair. You can protect yourself from this unexpected expense by replacing the worn-out belt sooner rather than later.

Continual Clicking.

Some furnaces give off a rapid series of clicks when they flip on and off. This is completely normal. That said, if the noise carries on longer than about one minute, this could suggest an electrical complication. Don't risk your home catching fire by a faulty electrical situation; call a furnace repair professional to solve the problem immediately.

Thwapping Sounds

The blower motor should perform without problems when the furnace activates. If you notice a thwapping sound that dramatically picks up speed as the blower gets going, this could mean something is stuck in the fan, and the blades are striking it with each rotation. A quick repair should be all that's required to get rid of this annoying furnace noise and protect against damaging the blower motor.

Rattling Furnace

A rattling furnace can be caused by multiple issues. It might be as simple as a loose door cover, so verify that option first. If the rattling continues, the most probable culprit is a failing blower motor. Consider this a warning sign to have your furnace repaired before it breaks down completely.

Whistling or Vibrating

When your furnace has an air intake vent issue, you will often hear a whistling or humming vibration sound. If the whistling or vibrating comes from a vent, your ductwork is likely loose, allowing conditioned air to leak. These aren’t emergency matters, but if you address it promptly, you’ll save money on your heating and cooling bills over the long haul.

Schedule Furnace Repair with Service Experts Heating & Air Conditioning

Are you unsure whether the furnace noises you hear align with these descriptions? Maybe nothing’s wrong, but for your peace of mind, the best thing to do is to call a professional. At Service Experts Heating & Air Conditioning, we have emergency furnace repair to get your system performing properly as quickly as possible. Rest assured knowing that we stand behind our work with a one-year, 100% satisfaction guarantee. If you’re dissatisfied with our work anytime in the next 12 months, we’ll fix it! For more information or to arrange a furnace repair visit, please contact a Service Experts office near you.