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There's a Loud Noise Coming From My HVAC System - What Could It Be?

Helms Heating & Air Conditioning - Tuesday, August 30, 2016
 outdoor heating and air conditioning unit

Uh oh! The HVAC unit is making noise. While noises coming from an HVAC unit are completely normal, there are some that you should listen out for. Some sounds may mean extensive repairs are needed to get the system working properly once again.


A squealing noise could indicate an issue with the blower belt. It may have come loose, began to fray, or came off. It could need to be replaced for fixed. The blower motor may require a complete replacement or a least a repair. Oiling the shaft bearings can stop the squealing noise as well. It’s also possible that the squealing stems from motor bearing problems.

Scraping Noise

A scraping noise coming from the unit means one of three problems is occurring. Firstly, the blower wheel may have come loose from the motor shaft, where it’s usually placed. The scraping is the wheel hitting the casing. While this isn’t a difficult problem to fix, it does need to be addressed and quickly. If it’s not tightened, the scraping noise will continue, and the pieces will grind together and become ruined. The pieces may need to be replaced if the wheel or shaft is too damaged. There’s possibility the motor mount broke and is now resting on the housing.


When you hear a banging noise, it might be because of dirt in the burners. Dirt accumulates on them and slows down the ignition process, which causes the gas to build up. Once it does ignite, you’ll hear a banging noise. Even a small explosion may possibly crack the heat exchanger, which is a costly repair. The air ducts may be expanding and contracting. The duct may be flimsy. The vents could be closed or too small while the air filter may need to be cleaned.

Rattling or Thumping

Generally, a rattling or thumping noise is an indication that the blower assembly or motor is bad

To figure out what the noise is coming from your HVAC system, inquire about an appointment from Helms Heating and Cooling today.