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Why Is My Furnace Making That Noise?

woman-listeningIf you’re asking this question, you’re already on the way to solving the problem. That you’ve noticed the furnace is making an odd sound is good news—not for the furnace, but for timely heater repair in Fresno, CA. The sooner you detect a strange sound coming from the furnace, the sooner you can call our technicians to investigate it and find out what repairs may need to be done. It always pays to move fast on potential furnace problems because it helps avoid safety concerns, the trouble getting worse, a more expensive repair, or the furnace breaking down entirely.

A malfunctioning furnace can make several types of noises. Below we’ll look at some of the more common. Please leave the actual diagnosis of the malfunction to our professionals, however.

Metal-on-Metal Clanging and Banging

A sharp clanging sound, like one piece of metal colliding with another, isn’t something you want to hear coming from any appliance in your home, certainly not the furnace. What this noise probably means for your furnace is that the fan in the blower assembly is loose or one of its blades has become bent so it’s striking the outside casing. This will cause extreme damage to the air handler if it is not repaired soon, so shut off power to the furnace and call for assistance.


Does it sound like some part has come loose in the furnace and is bouncing around? That may be the problem. It could also be screws that are starting to vibrate loose, and this is something you’ll want fixed before anything does come loose. But the rattling might also be a loose panel door, so check to see that it’s latched securely.


Each time a gas furnace’s burners ignite, they make a small whoosh sound. This is normal and you’ve heard it many times before. But if this sound turns into a surprisingly loud and startling boom, it means that too much unburned gas is collecting in the combustion chamber before the burners ignite. This could be from delayed ignition, dirt and grime on the burners, or problems with the flame sensor.

Shrieking and Grinding

These mechanical noises are warning about blower fan motor failure. A shrieking sound indicates the bearings in the motor are either dirty or wearing down. If the bearings wear out completely, the motor will soon overheat and burn out. Professionals can replace the bearings to prevent this and rescue the motor. Grinding usually warns that the motor is already burning out and needs a replacement.


Clicking is a normal sound during start-up. But it shouldn’t continue or become loud and constant. This amount of clicking can come from a range of different issues in the furnace. It might be stuck gas valves, a failing electronic ignition system, loose electrical connections, or even a cracked heat exchanger. Let our professionals get to the bottom of the problem and restore your furnace.

Call Purl’s Sheet Metal & Air Conditioning when you need great heating system repair. “Quality Is the Cornerstone of Our Success” since 1952.

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