Why is your aircon so noisy?
Is your aircon keeping you up at night with a rattle you can’t switch off? Many Jurong West and Jurong East HDB flats with two to four wall-mounted units get this at some point.
A healthy aircon makes a steady hum and a soft rush of air. Rattling, buzzing, grinding or clicking means something has come loose, worn out or started to fail.
Most noise faults are cheap to fix early and expensive to ignore. We’re Aircon Servicing Jurong, the Jurong arm of Cool Earth Aircon, which Brian started in 2007. Noisy aircon repair starts from S$60, with a fixed quote before work.
Here’s how to tell what your aircon is trying to say.
Common noises and what they mean
| Sound | Likely cause | What we check |
|---|---|---|
| Rattling | Loose cover, panel or ledge mounting | Screws, brackets and vibration pads |
| Buzzing from the outdoor unit | Weak capacitor or sticking contactor | Capacitor and magnetic contactor test |
| Grinding or squealing | Worn fan motor bearings | Indoor and outdoor fan motor |
| Clicking at start-up | Relay or control board fault | Relay and PCB control board |
Rattling
A rattle usually comes from one of three places:
- A loose front cover
- A screw that has backed out
- Debris inside the unit
On the outdoor side, a cracked condenser fan blade or a loose bracket on the aircon ledge will rattle as the fan spins. Anything that spins at speed turns a small looseness into a loud noise.
Buzzing
Buzzing from the outdoor unit often comes from a weak capacitor or a sticking magnetic contactor. Both help start the compressor and fan. A weak capacitor makes the compressor struggle, which can damage it over time.
Helpling’s Singapore guide notes that a failing capacitor can make motors buzz as they strain to start. Loose wiring can cause the same sound, so a quick test beats guessing.
Grinding or squealing
Grinding or squealing usually means worn bearings in the indoor or outdoor fan motor. The sound gets worse as the motor warms up, and the motor can seize if left.
Switch off and call us. Snowflake Aircon’s Singapore guide warns that a seized bearing can lock the motor and may trip your circuit breaker. Running a grinding motor only speeds up the damage.
Clicking at start-up
One click is normal. Repeated clicking can point to a faulty relay or a problem on the PCB control board.
Helpling’s guide also lists a struggling capacitor as a possible cause of clicking. We test the simple parts first, so you don’t pay for a board you don’t need.
Wobble or hum from the indoor unit
A blower wheel caked with dirt spins off balance. Cleaning it, often during a chemical overhaul, brings it back into balance.
Dirt builds up quickly in our climate. Coogle’s 2026 Singapore servicing guide suggests a general service every 3 months for HDB homes running 2 to 3 units daily, plus a chemical wash once a year. That routine keeps the blower clean before it starts to wobble.
Vibration on the ledge
Outdoor units sit on rubber vibration pads. When the pads perish or the bolts loosen, the whole unit shakes the ledge. New pads and tightened mounting fix it.
A few things to know:
- HDB wants outdoor units on the designated ledge, so the fix happens there.
- Billy Aircon’s mounting guide says good pads are usually neoprene or ribbed rubber, around 15mm to 20mm thick.
- A new pad set is a small cost next to a unit that shakes loose.
How we find the source
Noise travels along pipes and walls, so a sound that seems to come from the bedroom unit may start outside. We run the unit and listen at both ends. Then we test:
- The fan motor and bearings
- The blower balance
- The capacitor
- The contactor
Some noises only appear after a few minutes of running, so we give it time.
If the noise comes with weak cooling or a burning smell, switch the unit off and book a check. Our general aircon repair covers related electrical faults.
Ready to get some quiet back? Book your noisy aircon repair with us, and you’ll get a fixed quote before we touch a single screw.
