Aircon not turning on

What causes it, and what fixes each one

1. 1

   Flat remote batteries, or the wrong mode

   The most common reason of all, and the cheapest. A remote with weak batteries may still light its screen but not have the strength to send the signal across the room. Others are simply in fan or timer mode, or set above room temperature.

   The fix: New batteries, set the remote to Cool at 24 degrees, and point it at the unit from close up. If the display is blank or half-lit, that is your answer.

2. 2

   A tripped breaker, or a switch someone turned off

   No power reaching the unit, and nothing on it to show for it. A breaker can trip in a storm, or when something else on the circuit faults. A wall switch, or the switch beside the outdoor unit, gets turned off during painting and never turned back on.

   The fix: Look at the aircon breaker in your DB box, and any wall switch feeding the unit. A tripped breaker can be reset once, with dry hands. If it trips straight back, leave it off and call — resetting it is not safe. Aircon repair in Singapore

3. 3

   A light on the unit blinking a pattern

   Most brands report faults by blinking. The number of flashes, or which light is on, points to something specific — a sensor, a fan motor, a communication fault between indoor and outdoor. The same pattern means different things on a Daikin, a Mitsubishi and a Midea.

   The fix: Count the blinks, note which light is doing it, and send that with the brand and model over WhatsApp. It often narrows the fault before we travel, so we arrive with the right part. Aircon repair in Singapore

4. 4

   A failed capacitor or contactor at the outdoor unit

   The indoor unit lights up and responds, but nothing cools and the outdoor unit sits silent or hums without starting. Two ordinary wear parts sit behind this, and both fail more often as a unit ages.

   The fix: A diagnostic visit. These are cheap parts and a satisfying repair — a unit written off as dead often runs again the same visit. Not a DIY job at any level: there is stored charge inside an outdoor unit even after the power is off. Aircon repair in Singapore

5. 5

   A dead control board

   The board receives the remote signal and decides what runs. Power surges, lightning, damp and age all kill them. Signs are a unit with confirmed power that does nothing, no beep from the remote, or a light that blinks and never clears.

   The fix: Boards can sometimes be replaced and sometimes not, depending on whether the part is still made. We price it as one number and tell you how it compares with a new unit — past ten or twelve years, a board is often where replacing beats repairing. Aircon repair in Singapore

Aircon not turning on — questions

Why is my aircon not turning on but has power?

If a light or display is on, power is reaching the unit and the problem sits between the remote and the board. Start with fresh batteries and check the mode is Cool. If the remote is fine and the unit still ignores it, the board or its receiver is usually the cause.

Why is my air conditioner suddenly not turning on?

Most units that die suddenly are not broken. Flat remote batteries, a mode that got changed, a breaker tripped in a storm, or a wall switch turned off during a clean account for the large majority of them. Check those four before assuming a fault. If the power is confirmed, the batteries are fresh and it still does nothing, then it is a real fault — usually a capacitor, a contactor or the control board.

What to do if the aircon won't turn on?

Work through four checks, in this order. Put fresh batteries in the remote and point it from a metre away, set the mode to Cool at 24 degrees, look at the aircon breaker in your DB box and reset it once with dry hands if it has tripped, then check the wall switch and the switch beside the outdoor unit. If it still will not start, stop there and call. A diagnostic visit is $50, free if we go on to do the repair.

What does a blinking light on my aircon mean?

It is a fault code. The number of blinks, and which light is blinking, points to a specific fault, and the meaning differs by brand. Count the pattern and send it with the brand and model — we can often narrow the fault before we travel.

How much does it cost to repair an aircon that will not turn on?

The diagnosis is $50, free if we do the repair. The repair itself is quoted as one price for parts and labour before any work starts. Small electrical parts are at the cheap end, a control board at the expensive end. On an older unit we will say when replacing makes more sense.

Should I repair or replace an aircon that has died?

It comes down to the part and the age. A capacitor, contactor or fan motor is nearly always worth repairing. A board or compressor past ten or twelve years usually is not — you would spend a large share of a new unit on an old one. We give you both numbers and you decide.

How do I force my AC to turn on?

There is no safe way to force it, and nothing you should bypass to make it run. A unit that will not start is either not getting power, not getting the remote signal, or shutting itself down because something is wrong — and pushing past that last one turns a cheap repair into an expensive one. What you can safely do is the four checks: fresh remote batteries, Cool mode at 24 degrees, a tripped breaker reset once with dry hands, and the wall switch. Do not open the isolator box, the outdoor casing or the indoor control box, and do not touch wiring or terminals. There is mains voltage inside, and stored charge that stays live after the power is off. Past those four checks it is a technician's job.

Can I reset my aircon myself?

You can take the batteries out of the remote for a minute, and switch the unit off at the wall and back on after five minutes. That is as far as it safely goes. Do not open the isolator, the outdoor unit or the control box — there is mains voltage inside.

What is the 3 minute rule for aircon?

Most aircons will not restart the compressor for about three minutes after it stops. It is a built-in delay that stops the compressor starting again against pressure that has not settled, which is what wears one out. So a unit that looks dead right after you switched it off is often just waiting. Give it five minutes before deciding anything is wrong. The delay cannot be skipped, and there is no reason to want to.