Air Conditioner Noises and What They Usually Mean
Every AC makes some noise. The problem is when it makes a new one. Here are the sounds we hear about most often in Toronto, and what’s usually behind them.
Buzzing or humming, but the fan doesn’t spin
Most often a failed run capacitor. The motor gets power but not the boost it needs to start. Turn the AC off at the thermostat; running it like this can overheat the compressor. Capacitors store a charge, so this one is for a technician.
Clicking that keeps repeating
A single click at start-up and shut-down is the contactor or a relay, and it’s normal. Rapid repeated clicking can mean a failing contactor, a thermostat problem, or a compressor trying to start and tripping out.
Squealing or screeching
On the indoor side, a worn blower motor bearing or, on older furnaces, a belt. On the outdoor unit, a fan motor bearing. High-pitched screeching from the compressor at start-up can mean high internal pressure; shut it off and call.
Rattling
Loose panels, a twig in the fan, or the unit not sitting level on its pad. Sometimes it’s the copper lines vibrating against the house. Easy fixes, but check them before they rub a hole in a line.
Hissing or bubbling
Can indicate a refrigerant leak, especially if cooling has dropped off. A brief hiss when the system shuts off is normal pressure equalizing.
Banging or clanking
A loose or broken part inside the compressor or a fan blade hitting something. Turn it off right away.
Gurgling inside
Usually water in the condensate drain or a partly plugged trap. Clear the drain before it overflows.
When in doubt, turn the system off and give us a call at 647-657-2977. More on our AC repair services in Toronto and the GTA.
