Normal AC Sounds

A healthy air conditioner makes a consistent hum when running and a soft click when it cycles on and off. These are normal.

Sounds That Need Attention

Banging or Clanking

Usually a loose or broken part inside the compressor or a loose blower fan blade. Shut the system off and call a technician — running it can cause further damage.

Squealing or Screeching

Often a worn fan belt (on older systems) or a failing motor bearing. The system can usually run briefly, but schedule service soon.

Hissing

A refrigerant leak. You may also notice ice on the refrigerant line or reduced cooling. Turn the system off and call for service — refrigerant leaks don't fix themselves.

Rattling

Loose panels, debris in the outdoor unit, or a loose fan blade. Check the outdoor unit for leaves or sticks first. If the rattling continues with nothing visible, schedule a service call.

Clicking That Won't Stop

A single click at startup and shutdown is normal. Repeated clicking during operation usually means a failing relay or control board.

Bubbling or Gurgling

Air or moisture in the refrigerant line. Often accompanies a refrigerant leak.

When to Shut It Off Immediately

Banging, hissing, or any noise accompanied by burning smell — shut the system off at the thermostat and the breaker, then call for service.