Aircon Troubleshooting · Singapore · Updated June 2026
Why Is My Aircon Not Turning On?
No response usually means a power issue — a tripped breaker, a flat remote, or the isolator off. If power’s fine, it’s commonly a capacitor, a safety cut-off, or the control board. Here’s how to tell which — and how we fix it.
The short answer
An aircon that won’t switch on is most often a power problem — a tripped breaker, the wall isolator switched off, or flat remote batteries. Check those first. If power is confirmed and it still won’t start, the usual culprits are a failed capacitor, a full-drainage safety cut-off (some units stop to prevent overflow), or a faulty PCB/control board — all of which need a technician.
Quick diagnosis by symptom
Match what you’re seeing to the likely cause and typical fix.
| What you notice | Likely cause | Fix | Cost |
|---|---|---|---|
| No power, no lights at all | Tripped breaker / isolator off | Reset power (DIY) | Free |
| Remote dead but unit has power | Flat batteries / wrong mode | Replace batteries (DIY) | Free |
| Powers on but stops; error light | Drainage safety cut-off | Chemical wash + drain clear | from $110 |
| Hums or clicks but won’t start | Failed capacitor | Repair (diagnosis first) | from $50 |
| No response despite power | Faulty PCB / fuse | Repair (diagnosis first) | from $50 |
Common causes — and the fix for each
From simplest to most involved — work through them in order.
Tripped breaker or isolator switched off
The most common cause. No power reaches the unit — check the DB box for a tripped breaker and make sure the wall isolator next to the unit is on. Reset it once; if it trips again, stop and call.
Free — see the checks belowFlat remote batteries or wrong mode
The unit has power but never gets the command. A flat remote battery or the unit set to “Fan”/timer instead of “Cool” makes it seem dead. Replace the batteries and check the mode first.
Free — see the checks belowDrainage-full safety cut-off
Some units stop running when the drainage tray is full, to prevent overflow into the room. A blocked drain trips a float safety switch — clearing the blockage brings the unit back.
Chemical wash from $110Failed capacitor
The most common electrical fault. A failed capacitor means the unit hums or clicks but won’t start. It needs proper diagnosis and a replacement part.
Aircon repair from $50Faulty PCB / control board
A dead or glitching control board stops the unit responding at all — power is fine and the remote works, but nothing happens. The board needs testing and, often, replacement.
Aircon repair from $50Blown fuse
An internal fuse has failed and cuts power to the control board, so the unit appears completely dead. A technician can test and replace it as part of a repair.
Aircon repair from $50Wiring or contactor fault
Loose, corroded, or burnt wiring — or a failed contactor — breaks the electrical circuit so the unit can’t start. This needs proper diagnosis and is not safe to fix without tools.
Aircon repair from $50Compressor or motor failure (older units)
On ageing units, an end-of-life compressor or motor can prevent start-up entirely. Repeated faults on an old unit can mean replacement is the better value — we’ll advise honestly.
Aircon repair from $50What you can check yourself first
These are free and safe to try before booking a visit.
- 1Check the distribution board for a tripped breaker, and that the wall isolator switch near the unit is ON.
- 2Replace the remote batteries and confirm the mode is set to “Cool”.
- 3Switch the unit off at the breaker for 5 minutes, then back on, to clear a glitched control board.
- 4Look for a blinking light or error code on the indoor unit and note the pattern — it tells the technician a lot.
- 5Make sure nothing else on the same circuit has tripped the breaker.
When to call a technician
If power, the remote, and the mode are all fine, the fault is inside the unit — a capacitor, a control board, a fuse, or wiring — and none of those are safe or possible to fix without tools and training. A breaker that keeps tripping or any burning smell is a particular warning sign: stop, leave it off, and call, because forcing it back on risks the wiring.
We diagnose the exact cause on-site, tell you the price before any work, and can usually fix it the same day. Aircon repair across Singapore — diagnosis from $50, waived when you proceed with the repair.
Other aircon problems
Aircon won’t turn on — FAQs
Why won’t my aircon turn on at all?
My remote isn’t working — is the aircon broken?
Why does my aircon turn on then shut off immediately?
What does a blinking light or error code mean?
Is it safe to reset the breaker myself?
How much does it cost to fix an aircon that won’t start?
Could a blocked drain stop my aircon turning on?
Aircon won’t start? We’ll get it running.
Same-day diagnosis across Singapore. Transparent pricing — you know the cost before we start.