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Clawson Heating & Air Conditioning Blog

Furnace Sounds That Should Probably Scare You


Okay, so, no, we aren’t that kind of company. We aren’t here to scare you into making a purchase with us. The fact of the matter is, there are certain sounds that a furnace might make during its operation that you can be tempted to brush off, but really, they signal that it’s time to call in a professional.

Your furnace is never going to be silent, of course. You will hear the whoosh of air coming through your vents, maybe some very minor rattling as the air travels through your furnace’s air ducts. These are normal, day-to-day, operational sounds.

We’re talking about sounds that you don’t normally hear, though, from screeching to hissing or clicking. Read on to learn what each of these can mean, and then please give us a call ASAP if you notice any of them.


We have a bit of good news. Screeching can actually be relatively mild. No, you shouldn’t ignore it, but it doesn’t mean that anything has gone terribly wrong yet.

In most cases, what you’re hearing is the friction of the motor against the motor bearings for the blower fan. Over the years, lubrication wears down, which increases the friction, and this is what causes the sound.

This is a relatively simple “repair” for our team–we’ll come in and lubricate the motor bearings and resolve the problem. We can also check on the rest of your system during this time to ensure nothing else is amiss.

Hissing or Clicking

This sound can be a bit more serious, and we really think it’s wise to shut down your system and give us a call as soon as you hear either, partially if you’ve never heard these sounds coming from your furnace before and you have a gas-powered furnace.

Your furnace has a component called a heat exchanger–this is where combustion gases collect in order to actually generate heat. The blower fan blows air over the heat exchangers to bring air into your home.

If the heat exchangers get damaged, which can happen in an aging or an ill-maintained furnace, the combustion gases can leak out and have the opportunity to enter your indoor air.

As a result, you might hear hissing as the combustion gases seep out. Or, you may hear a clicking sound as the heat exchangers cool down and contract–it’s the cracks closing back up.

The problem with being exposed to combustion gases in your indoor air is that it opens the door to carbon monoxide poisoning, which can be very dangerous. CO poisoning actually leads to hundreds of illnesses and even fatalities in homes in America each year.

In addition to having carbon monoxide detectors installed in your home, the best preventive step you can take is to take good care of your furnace and all of your gas-powered appliances.

By this, we mean staying on top of your annual furnace maintenance appointments–this will help keep your furnace safe, but will also help it work as efficiently and effectively as possible, for as long as possible!

For expert furnace service in Tigard, OR, look no further than Clawson Heating & Air Conditioning. Contact us today!

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