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Why Is My AC Making Noise?

Close up of HVAC system external unit.

Newer AC models are more energy-efficient, smarter, and quieter than ever before. The latest high-efficiency units are designed to keep noise at a minimum, so any sounds out of the ordinary could be cause for concern. Ignoring rumbles and bumps could lead to catastrophic equipment failure.


Humming is a pretty benign noise, right? Most of the time, the answer is yes. However, new units should be fairly quiet. That hum could spell trouble in the form of:

  • Loose ductwork

  • Wiring

  • Electrical failures

If the humming is followed by a failure to start, the motor might be failing. At Site:BusinessName}, our technicians will help you identify the issue and prevent more serious problems from developing.

Banging and clanking

A bang or loud clanking noise can be pretty alarming. This is usually a sign that something has become loose or is out of balance. Your fan or blower might be bumping into another part. The piston could be broken. Less commonly, the racket could indicate the need for a new compressor.

You’ll need a professional diagnosis to quiet your AC and keep your home cool and comfortable.


If your AC unit sounds like it’s got something rattling around in it, it probably does. Something might be loose, like a twig or some leaves. However, it could be something more severe, such as screws or bolts.


An occasional click as your air conditioner powers on and off is normal. Constant clicking is not and could indicate that your thermostat or another electrical component is failing.

Whistling, Squealing and Screeching

A squealing noise is a sign that the blower or fan motor is going out. However, a whistling or screaming noise might indicate that your refrigerant is leaking, or the internal pressure could be high.

There’s no good time to have your air conditioner go out. If you hear something unusual, turn it off until it can be checked out. Regular service can often catch potential problems before they lead to noisy operation or replacement. Schedule your service with West Coast Air Conditioning at (805) 954-9195 to keep you cool and comfortable this summer season!