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Kilowatt Heating, Air Conditioning and Electrical Blog

Warning Sounds From a Furnace in Trouble


We’re probably going through the last spell of “cold” weather here in Southern California, and that means you’re in the final stretch of depending on your furnace on a regular basis. It’s also a time when a furnace is more likely to have malfunctions because of the accumulation of strain during the season. That fall maintenance visit seems distant, especially when you’re getting ready to schedule AC maintenance.

It’s a wise idea to keep a close watch on your furnace for signs it may be in trouble. Or in this case, a close listen. Odd sounds are one of the ways you can tell you may need professional repairs for your furnace.


You can expect to hear some clicking from the furnace each time it turns on. This is the sound of the igniter turning on the burners, and it’s nothing to worry about. But clicking at other times, or clicking that’s become loud and common can point toward multiple issues. It might be the sound of stuck gas valves or a failing ignition system. It can point toward a range of electrical failures (yes, a gas furnace uses many electrical components). It could even warn of a crack in the heat exchanger, which is a serious problem that needs immediate attention from professionals. We recommend you shut off the furnace at the furnace switch and call for repair technicians.


This startling noise, like a rush of air or a small explosion, is likely coming from a build-up of unburned gas inside the combustion chamber. When the gas finally lights, it will create this booming sound. Unburned gas should not build-up this much, not without the burners igniting it. If this sound is occurring, something is delaying burner ignition or there is a fault with the flame sensor that should shut off gas flow if the burners don’t ignite.


If you hear rattling from the furnace, first check its front panel to see if it’s loose. The problem could be as simple as that. If the panel is secure, the noise probably indicates loose parts inside the furnace or inside the blower fan. You’ll want this fixed soon because the damage will worsen if it continues.

Metal-on-Metal Clanging

This is another startling sound, and the cause is probably in the blower assembly: a fan blade is bent or the fan is loose and is striking the casing. Shut the furnace off immediately to prevent further damage to the components and call for repairs. 

Mechanical Shrieking and Grinding

These noises come from motors that are either wearing out or burning out. The shrieking sound is bearings that are dirty or almost worn down. If the bearings give out, the motor won’t last much longer. Grinding usually indicates a motor that has already overheated and is burning out; you might smell an acrid odor from the vents along with this sound. The motor will need to be replaced.

For your heating in Burbank, CA, you can rely on our team to get the job done. We offer emergency response!

Kilowatt Heating, Air Conditioning and Electrical serves Los Angeles and the San Fernando Valley. Call our certified service technicians 24/7 for exceptional customer service!

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