Ross and Witmer 
Originally published in July 2013, updated September 2016
When the familiar hum of your Charlotte, NC home’s air conditioner is interrupted by unfamiliar noises, it’s a good idea to be concerned. Loud or unusual noises within the compressor may be a sign of trouble and should be tended to by a professional as soon as possible. Here are some of the more common types and causes of A/C compressor noise.
7 A/C Compressor Noises that Need Professional Attention
- Banging or clanking: These types of noises are often caused by a loose part or system component, such as a connecting rod or piston pin. Usually, the only solution if to replace the compressor.
- Clanking or rattling: Loose internal mounts can cause rattling and clanking from the compressor. The sound probably means that the motor has come loose and is moving around inside the sealed compressor can.
- Hissing or bubbling: A serious refrigerant leak can produce hissing noises in the compressor. If you detect this noise, have the compressor checked as soon as possible since it could mean that refrigerant is being released to the environment. Leaks in the refrigerant lines can also cause hissing and bubbling noises that are not as severe.
- Clicking: Damaged or malfunctioning controls and relays can cause a clicking noise at the compressor as these components try but fail to function.
- Ticking, rattling, clicking or rumbling: A loose piece of hardware could cause sounds like this to occur near the compressor.
- Hissing or screaming: A loud hissing or screaming noise from the compressor could indicate dangerous levels of pressure inside the unit. If you hear noises such as these, shut the system off and contact your local trusted HVAC service provider.
- Humming: A hard-to-start compressor that makes humming noises could be low on oil. The sound could also be caused by a failed starting capacitor. A compressor that hums but will not start could mean a seized-up compressor motor.
Founded in 1945, Ross & Witmer continues to be a premier source of expert HVAC services in Charlotte, Gaston, Mecklenburg and Union. Contact us today for more information on identifying A/C compressor noise and for professional maintenance and repair that will stop the noise and get your cooling system working again.
