What Is That Noise? A Quick Guide
Is your aircon suddenly louder than the telly? We handle noisy aircon repair in Jurong West and Jurong East, and the sound usually tells us where to look before we open a single panel.
Different sounds point to different problems. Here is what we usually find.
| Sound | Where | Likely cause |
|---|---|---|
| Rattling | Indoor | Loose cover, screw or cracked blower wheel blade |
| Rattling or vibration | Outdoor | Loose grille, worn bracket or anti-vibration pads |
| Buzzing | Outdoor | Weak capacitor, worn contactor, struggling compressor |
| Clicking | Indoor or outdoor | Relay switching repeatedly, control fault |
| Grinding or squealing | Indoor or outdoor | Worn fan bearing or fan motor |
| Gurgling | Indoor | Water or air in a partly blocked drain line |
Timing matters too. According to the Singapore site aircons.sg, a single click as the compressor starts is normal relay action, but continuous clicking points to an electrical fault.
Indoor Unit Noises
Inside the room, most noises come from the fan section. A blower wheel that is caked with dirt can go off-balance and wobble. A cracked blade can tick against the housing every turn. A fan motor with a dry bearing starts to whine and then grind.
Bedroom units are where noise bothers people most, since they run all night. If the sound started after a recent knock or an aircon servicing visit, a cover may simply not be clipped in properly. That is a quick fix.
Before you call, try these three checks:
- Press gently around the front cover to see if the rattle changes.
- Look at the filters. Quiet.sg, a Singapore noise-control site, notes that dirty filters make the fan motor strain, and it suggests cleaning them monthly.
- Note whether the sound happens at start-up, on full fan or all the time.
Outdoor Unit Noises on the HDB Ledge
Outdoor units sit on the aircon ledge outside your window. Over the years the brackets loosen and the rubber pads under the unit harden or crack. Vibration from the condenser fan and compressor then travels into the wall. You may hear it as a hum through the bedroom, and so may your neighbours above and below in the HDB flat.
Age plays a part. VD Aircon Services says units are often within noise limits when new, but 4 to 6 years in, worn compressor bearings begin to shake the bracket. The unit itself may not be loud. The bracket carries a low-frequency hum into the wall, and that is what neighbours hear.
Here is what we do on the ledge:
- Check the bracket bolts for looseness or rust.
- Replace hardened or cracked pads.
- Inspect the fan blade and motor.
- Listen to the compressor start.
Many ledge noises are fixed in a single visit. If the bracket itself is corroded, it needs replacing. Grade 304 stainless steel is the standard material for HDB brackets, according to Saces.sg’s 2026 HDB installation guide.
One more thing worth knowing: aircons.sg points out that there is no separate NEA decibel limit that applies between two HDB units. The NEA boundary guideline is measured at the site boundary. So a friendly word with your neighbour, plus a quick fix on your side, usually works best.
When a Noise Means a Part Is Failing
Some sounds are early warnings:
- Buzzing that gets louder often means a capacitor is weakening. When it fails, the unit stops cooling.
- Grinding means a bearing is wearing. Left alone, the motor can seize.
- Repeated clicking without starting suggests a relay or control problem.
Capacitors do not last forever. Aircons.sg puts their typical lifespan at 4 to 6 years in Singapore heat, so an older unit with a new buzz is a good suspect. A 2026 price guide from Saces.sg lists a capacitor repair at roughly $80 to $150 including labour.
Catching these early is usually cheaper than waiting for a breakdown. If the unit has already stopped, see our aircon repair page.
Getting the Best Diagnosis
Noises can come and go. A short video with sound is the best clue you can give us.
When it happens, do this:
- Record a short video with sound and send it on WhatsApp.
- Tell us if it is worse at start-up, at night or when the compressor kicks in.
- Mention how many units you have, so we can tell which one is the culprit.
Before the visit, read how to prepare your home for the technician, especially clearing window access to the ledge. Then send us that video on WhatsApp, and we will sort out your noisy aircon repair as soon as we can.
