That Noise in the Compressor of Your A/C: So What Does The Banging, Chatter or Buzzing Mean?

That Noise in the Compressor of Your A/C: So What Does The Banging, Chatter or Buzzing Mean?

That Noise in the Compressor of Your A/C: So What Does The Banging, Chatter or Buzzing Mean?If you call your HVAC contractor to report a noisy A/C compressor or condensing unit, there’s a good chance the customer service representative will ask you to describe the noise and identify where it’s coming from, in order to give the technician more to work with. This guide to common A/C compressor noises will help you describe the problem, as well as understand why your A/C or heat pump might need service or even replacement.

Here’s a guide to help you when you hear an A/C compressor noise, and what it might mean for your upcoming repair or potential replacement.

Banging or clanking

This can be a sign you have loose parts such as the crankshaft, rod, piston or pin. If your system is older, this might be a fairly simple repair. However, newer A/C compressors are typically in sealed units, which likely necessitates a replacement. This noise can also mean that you have loose motor mounts, which means the unit will need to be replaced.

Bubbling or hissing

If you hear a loud hissing noise that ends abruptly, you may have a major refrigerant leak from the high-pressure side. If so, the refrigerant is being released into the atmosphere. However, it’s more common to hear a more gentle, sustained bubbling sound, indicating a smaller refrigerant leak. In either case, refrigerant leaks require immediate professional attention, since they pose an environmental hazard and will result in reduced efficiency and performance, and eventual system breakdown.


Buzzing may be heard at the outside fan motor and could signal that the motor is wearing out, and/or electrical issues need to be addressed.

A loud scream or sustained hissing

This A/C compressor noise is distinctive and means internal pressures may be excessive, due to a failed high-pressure sensor. Turn the unit off ASAP and call a professional.


If clicking can be heard at the compressor/condenser or the indoor air handler unit, the relays and controls may be going haywire.

General clicks, rumbles, ticks and rattles

Then there are the miscellaneous compressor noises that can indicate moving parts such as loose refrigerant tubing, shipping bolts or broken springs.

Have you noticed a strange A/C compressor noise? Please contact us at Powers Heating & Air. Our qualified technicians have expertly diagnosed and repaired Peachtree City area A/Cs since 2001.

Our goal is to help educate our customers in Peachtree City, Georgia and surrounding areas about energy and home comfort issues (specific to HVAC systems).

Image courtesy of Shutterstock

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