Why Your HVAC System Is Being Noisy (And How to Fix It)

If you find yourself hearing noises coming from your indoor unit, air handler, or furnace, you are not alone! These are common complaints within the HVAC field and the bustling normally falls into one of six different categories. Let’s take a look at these below so you are better able to identify and resolve this problem.

Metal Scraping

If you find yourself hearing loud, scraping sounds that you may believe is metal hitting other pieces of metal, turn the system off immediately. A common cause is a loose blower wheel that has detached from the motor shaft. The sound is generally the wheel hitting the blower housing. Additionally, this noise could indicate that the wheel is broken. Of all potential categories, this one is the most alarming.

Thumping and Vibrations

Often compared to the sounds that come from a off-balance washing machine, these noises indicate that the blower wheel needs to be realigned. Additionally, the motor may be out of balance. While this isn’t an imminent threat, it shouldn’t be ignored for too long as it can create other problems within the system.


If there doesn’t appear to be any problems with the unit working properly, loud humming could just indicate a noisy transformer. While some are louder than others, they all generally hum to some degree. If the unit does not appear to be working at all, it may be due to a bad indoor fan motor or capacitor.

Rattling or High-Pitched Sounds

These sounds could point towards problems with your heat pump. This is generally due to a concern with the refrigerant flow or noisy check valves and metering devices. When the sound begins to increase and it does not appear to be due to the air filter, a professional should be contacted.

Pop or Banging

For some systems that have sheet metal ductwork, this sound may be from the system fan starting or stopping. While this is normal in some sense, it could also be due to an undersized duct, a clogged filter, or flimsy ducts.


Rumbling usually indicates a problem with the burner. If this is associated with your gas or oil-fired appliance, it requires service attention immediately. Equipment should be turned off right away as it could pose significant danger to occupants.

These six noise categories are common complaints among HVAC systems. If you find yourself hearing one of these, try checking the associated parts. If you do not have the experience to fix the issue yourself, contact an experienced professional like Doctor Fix-It for help.


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