31/08/2026
Strange Noises Your Air Conditioning Makes (And What They Mean)
Strange Noises Your Air Conditioning Makes (And What They Mean)
A bit of a hum and a soft whoosh of air is normal. A rattle, a screech, or a bang coming from your indoor or outdoor unit is your air conditioning trying to tell you something. Most of these noises won’t fix themselves, and a few of them mean you should switch the system off and get someone to look at it before you use it again. Here’s a rundown of the most common ones we hear about, and what’s usually behind them.
Clicking
A few clicks when the system starts up or shuts down is completely normal, that’s just relays switching or metal expanding and contracting as it heats and cools. If the clicking is constant, repetitive, or happening throughout the cycle rather than just at start and stop, it’s often an electrical or relay fault worth getting checked.
Buzzing
A steady buzz can point to a few different things: a loose part vibrating somewhere in the unit, debris caught in the outdoor fan, or an electrical issue like a failing contactor or capacitor.
Rattling
Usually mechanical. Loose screws or panels, a fan blade that’s come slightly out of line, or leaves and twigs that have found their way into the outdoor unit will all rattle away happily until someone takes them out. Worth a quick look outside, if there’s obvious debris in the unit, switch it off and clear what you safely can before calling a technician.
Banging or clunking
This one gets our attention. A loud bang or clunk, especially from the outdoor compressor unit, can mean a part has come loose internally or the compressor itself is under strain. This isn’t a “wait and see” noise, turn the system off and get a technician out before running it again.
Whistling
A whistling sound is often airflow related, a blocked or dirty filter forcing air through a smaller gap than it should, or a duct that’s come loose or has a gap somewhere. Filters are an easy first check; anything in the ducting will need a closer look.
What to do when you hear something off
For soft, mechanical-sounding noises like a bit of rattling from debris, a quick check and clean is often all it takes. For anything electrical, switch the unit off and don’t keep running it, some of these faults get worse (and more expensive) the longer a system keeps operating under stress.
If your air conditioning’s making a noise that doesn’t sound right, give the team at Ford & Doonan a call. We’ll figure out what’s actually going on and get it fixed properly, so you’re not lying awake wondering what that clunk was.
1800 AIR CON 
