Aircon making noise? Normal sounds vs the ones that matter

The short answer: soft clicks, faint gurgles and a gentle whoosh are normal split system behaviour. Rattles usually mean something’s worked loose. Grinding, squealing or banging mean switch it off and book a repair — running a failing motor or compressor makes the eventual bill bigger.

Sounds that are normal

• Clicking at start-up or mode change — relays and the reversing valve doing their job
• Gurgling or trickling — refrigerant moving through the coil, most audible right after start-up
• Creaks and soft ticks — plastic panels expanding and contracting with temperature
• A whoosh in heating mode every so often — the defrost cycle, explained in the heating guide

Sounds that mean “book a visit”

• Rattling or buzzing — loose panels, a vibrating outdoor unit mount, or debris in the fan. Minor now; wears parts if ignored.
• Clicking that never stops — a relay or control fault, sometimes electrical.
• Dripping-related slosh paired with water inside — that’s a drainage problem.

Sounds that mean “switch it off now”

• Grinding or screeching — a fan motor or bearing on its way out
• Loud banging or clanking — something has come adrift inside, or the compressor is in trouble
• Hissing— possible refrigerant escape; legally an ARCtick-licensed technician’s job to trace and fix

With those three, continuing to run the system risks turning a replaceable part into a replaced system. Switch it off at the remote (and the isolator if the noise continues), then book a repair— we diagnose, quote before fixing, and if the system’s age makes repair a bad deal, you’ll get the honest repair-or-replace numbers instead of a sales pitch.