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Serving the South Puget Sound and Western Washington Areas Since 1976

Serving the South Puget Sound and Southwest Washington Areas Since 1976

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Sunset Air Blog

Why Is My Furnace Making Strange Noises?

It can be somewhat alarming when your furnace starts making unusual noises. Your mind may dream up all sorts of nightmare scenarios that might be happening to your furnace. Really, though, how much trouble your furnace is in depends on the type of sound you’re hearing. Let’s run through some of the more common strange sounds you are likely to hear coming from your furnace.


Your furnace’s air handler is the part responsible for circulating warm air throughout the house. This puts the air handler motor under an extreme amount of friction, so to compensate it is equipped with lubricated bearings. These bearings allow the air handler to function without burning out from the strain. The problem is that the bearings will eventually wear out, causing a steady increase in the amount of friction the motor suffers. That is the source of the grinding sound you are hearing. If the bearings aren’t replaced, the motor will eventually burn itself out. If you hear this sound, turn the furnace off and call for repairs immediately.


If you hear a deep booming sound coming from your furnace, typically shortly after starting up, it is often the fault of a dirty burner assembly. As a burner assembly burns natural gas, carbon molecules build up on the burner assembly. If the assembly isn’t cleaned, the carbon buildup can eventually become bad enough that one or more of the jets fire later than they should. This causes that deep booming sound, as the jets finally ignite. You should have the assembly cleaned off right away if you notice this sound, as the buildup can eventually prevent the entire assembly from igniting.

If your furnace is making strange noises, call Sunset Air. We offer comprehensive furnace services throughout Olympia, WA.

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