Aircond noisy: what the sound means
What each aircon noise can mean, from humming and rattling to hissing, the checks you can do safely, and when to call a technician.
What the sound can tell you
This is general guidance. Different sounds point to different problems.
A hum or buzz can mean something is loose or electrical. Rattling or clanking usually means loose parts. Clicking or ticking points to an electrical fault. A hiss or whistle may be a refrigerant leak. Vibration or rumbling suggests loose components. Grinding or squealing points to worn bearings. Noise from the ducting can mean gaps in the duct.
Checks you can do safely
Switch the unit off at the isolator before touching anything beyond the filter.
Replace a clogged filter. Tighten loose screws and bolts. Clear debris from the fan blades.
When to call a technician
Leave refrigerant, compressor, and electrical work to a qualified technician rather than attempting it yourself.
Call a professional for persistent clicking, a burning smell, grinding or squealing, or a hiss.
Updated 4 Oct 2026