An air conditioner is never silent. Fans move air, refrigerant flows and metal expands as it warms and cools. The trick is to know your unit's normal sounds so that a new one stands out. Noise is often the earliest warning of a fault, and acting on it can prevent a bigger repair.
Normal sounds
- A soft whoosh of air from the indoor unit
- A gentle gurgle or flow sound when the compressor starts or stops
- A light click as the unit switches on or off
- A faint tick as plastic panels expand and contract with temperature changes
- Water dripping outdoors from the condensate drain
Sounds that deserve attention
Rattling or vibrating
Often a loose panel, a loose screw, debris in the outdoor fan or an unsecured pipe. Sometimes a fan blade is out of balance or a mounting bracket has loosened. Switch the unit off if it is severe.
Hissing
A steady hiss near the unit can point to a refrigerant leak, particularly if cooling has faded. A short hiss at startup or shutdown can be normal. See refrigerant leak signs.
Bubbling or gurgling that persists
Can indicate air or moisture in the system, or a drain problem.
Buzzing or humming
A hum that does not lead to the compressor starting suggests an electrical component, such as a capacitor, is failing. Loud buzzing from the outdoor unit warrants a prompt check.
Clicking that repeats
Repeated clicking without the unit starting can indicate a relay or control fault.
Squealing or screeching
Usually a fan motor bearing or belt-type wear. It tends to get worse, so do not ignore it.
Grinding or scraping
Serious. Switch off. It can mean failing bearings or a fan striking something. Running a unit while it grinds risks costly damage.
Safe checks
- Switch the unit off and look for loose covers, panels or items touching the outdoor unit.
- Clear leaves or objects near the outdoor fan, without reaching inside.
- Check that the unit is level and stable.
- Note when the noise happens: at startup, continuous, or only in one mode.
- Record a short video with sound for the technician.
When to book a repair
Book a visit if a noise is new, getting louder, accompanied by weak cooling, ice, smells or trips of the breaker, or if it comes from the compressor. For split units, our split AC repair page lists the faults we usually find. If a noise comes with warning signs, read about when AC repair cannot wait.
Need help with your AC or appliance?
Call or message us on WhatsApp. Tell us the appliance, its make and model if you have them, and what is happening. A photo or short video of the fault helps.
Available 24/7 · We aim to respond within 30 minutes · 6-month warranty on repair work
Frequently asked questions
Why is my AC louder than it used to be?
Dust build-up, loose parts or wearing bearings are common reasons. A service often finds the cause.
Is a dripping sound normal?
Water dripping outdoors from the drain pipe is normal. Dripping or running water indoors is not and needs attention.
Why does my AC make noise only when it starts?
A short start-up sound can be normal, but loud banging or buzzing at start-up may point to a capacitor or compressor issue.
Can I fix a noisy AC myself?
Tightening an accessible loose panel is fine. Anything involving fans, wiring or refrigerant should be left to a technician.
