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Serving All of Southern California Since 1954


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Greenleaf Heating & Cooling Blog

Beware These 4 Noises Coming from Your Furnace


It may not get as bitterly cold here in our part of the country as it does others, but that doesn’t mean we don’t need a fully functioning, efficiently operating furnace in our homes, right?

Hopefully, you’ve already scheduled maintenance for your furnace to ensure it works as effectively and efficiently as possible the rest of this fall and this upcoming winter. If you haven’t, however, it’s not too late!

Even with maintenance, it is possible that you’ll have some repair needs crop up every now and then–this is a normal part of wear and tear. The important part is that you know when to call for professional repair services. One of the biggest indicators is if your furnace is making some ominous noises. Read on to learn what these are.


In most cases, this sound is an indication that the lubrication has worn down on the motor bearings of your blower motor. This is a very natural part of wear and tear, and it’s something we check for during maintenance. However, whether it’s been a long time since your last furnace maintenance appointment or your heater is old (10-15 years old), this can lead to too much friction on the blower motor.

By the time you hear a screeching noise, you are in danger of your blower motor burning out, overheating, and your furnace shutting down as a result. Fortunately, this can be avoided by giving our team a call!


If you hear something that resembles metal on metal, then you probably are hearing metal on metal. You may be hearing a problem with the furnace’s blower wheel–you don’t want to let this continue, so contact our professionals right away to prevent further damage! More damage to the wheel means a more expensive repair need.

Banging or Booming

If you hear a “bang” or a “boom” come from your furnace when it starts up, then you probably have dirty burners. This probably sounds like a pretty benign problem, but it can potentially become dangerous if left unaddressed.

The noise you’re hearing is likely caused by a delay in ignition due to dirt and build-up. The gas builds up, then when it ignites, a small “explosion” occurs inside the furnace.

The problem with this is that it rattles the furnace to the point that more serious problems can happen, like a cracked heat exchanger, which can introduce harmful carbon monoxide into your home.

Cleaning the burner yourself is not something we recommend. There is too much room for error, and you shouldn’t have to spend more money in the long run. It’s always after to call in a pro if you’re dealing with gas.


In many cases, any rattling noise you hear coming from the area of your furnace might be something as minor as a panel on the cabinet coming loose. The solution can be as easy as tightening that panel with a screwdriver.

If you checked though and that’s not the case, then there may be loose components within your furnace. Even if your furnace seems to be working “just fine,” it’s still a good idea to have the system checked out by a pro to make sure nothing serious is going on.

For professional and reliable furnace repair in Pomona, CA, contact Greenleaf Heating & Cooling.

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