bee on flowerDoes it sound like a small beehive has taken up residence in your furnace? Don’t delay, because a furnace that makes a buzzing noise when running could have major problems, some of which could result in a total breakdown. If you catch the problem early enough, you may get away with a quick fix instead, like tightening loose equipment. Here’s what could be behind the strange noise:

Blower Motor Problems

The blower motor pushes the warm air from your furnace into the home. It’s the most common source of a buzzing noise in a furnace. The noise might occur when the motor is starting and stopping, or it might buzzing the whole time it’s running. Either way, the motor blower will need to be replaced. When it is, you’ll notice your home gets warmer faster.

Loose Parts

Sometimes buzzing is the sound of a part of the furnace vibrating or rattling against something it shouldn’t. Usuall.y this is caused by loose equipment. It could also be caused by something stuck inside the furnace. Your HVAC technician will inspect the whole furnace to look for the cause of the noise.

A loose part will need to be secured or else it will damage itself and whichever part of the furnace it is vibrating against. The most common loose part is the transformer. This is common on furnaces that have recently been installed. Though the transformer may also make a buzzing noise when it’s dying, so older furnaces can suffer this problem too.

First, your HVAC technician should attempt to secure the transformer. If it still buzzes afterward, it may need to be replaced.

Wobbling Ductwork

When you’re standing near the furnace, listening for that odd buzzing noise, does it seem to be coming more from the ductwork than the furnace itself? Then it’s quite possible the problem is loose ductwork that is wobbling from the pressure of the forced air.

This is a quick fix. Though, it is important to address this problem as soon as you notice it, as the ductwork may eventually work itself completely loose and fall down. Then you may have to replace the duct too. Plus, ductwork with gaps robs your furnace of efficiency by letting warm air escape. This problem is probably costing you in utilities every month.


Another common cause of a furnace’s buzzing noise is the capacitor. Normally, a capacitor problem is serious and the furnace’s motor won’t be turning. It will turn on and make noise, but the furnace ultimately won’t be heating your home well. This is a serious problem that can end up ruining your whole furnace if it is left unchecked.

Whichever problem is causing your furnace to buzz when running, it’s important to get a professional to look at it soon. Most of these issues are simple fixes or relatively inexpensive replacements. The blower motor and capacitor won’t chew into your maintenance budget too much. However, they will cause more serious problems if they don’t get the repairs they need.

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