What's that noise? HVAC Edition

June 26, 2017

Picture this: you're in your bed fast asleep and the air conditioner kicks on. All is good and well until, out of nowhere, you start to hear a noise. All air conditioners emit a little noise, but this is different, this noise means something is up. If you haven't had your summer maintenance check, you may have no idea what that noise could be. Here's a guide to help you self-diagnose any noises to figure out how soon you need to call in the experts.


  • Squealing: A squealing sound is very often related to your blower motor. Motor belts are A relatively inexpensive repair but should be replaced before they break, otherwise your blower will no longer run, making for a hot night. The other issue squealing can indicate is motor bearing problems. These can often be solved by adding a lubricant – be sure to check with your local home improvement store as most household lubricants are too lightweight for this issue.
  • Rattling/Banging: Rattling is a strong indication that something has come loose in your system. This issue should be fixed quickly before any damage is cause to the part or it disconnects completely. It could also mean the blower is out of alignment.
  • “Thwapping”: This unsettling noise sounds like something stuck in a bike tire. If you hear “thwapping,” something is likely stuck in your blower blades. This is not necessarily a critical issue, but it could decrease the life of your motor.
  • Clicking: Clicking should happen when your system turns on or off. That's normal. Repeated clicking could be a sign of a defective relay.
  • Hissing: While the sound of air rushing through vents is common place, vents hissing is not. Hissing is a sign that your ductwork isn't properly sealed or a coolant leak. If coolant lines are leaking, you should get an HVAC specialist in as soon as possible.


If you're worried about noises coming from your ducts or air conditioning, call A.J. Perri TODAY! A specialist can diagnose and fix the problem so you can rest easy with peace of mind.

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Last Updated: June 07, 2024