The aircon will not start properly, and a small light on the indoor unit is blinking at you. Or the display shows a letter and a number you have never seen before. It is clearly trying to tell you something, and the remote gives you no way to ask what.
That blinking light or code is the unit's own self-diagnosis. It is useful, but only if you handle it correctly: write it down, do not keep resetting it, and give it to the technician before they arrive. This post covers what the signal is, how to record it, the few safe checks that are worth doing first, and what it costs to have it looked at, using only the prices on our published price list.
What a blinking light or code actually is
An aircon has a small control board that watches its own sensors: the temperature probes, the fan motors, the drain, and the link between the indoor and outdoor units. When something reads wrong, the board stops the unit, or limits what it does, and reports the fault. On some units that report is a code on a display. On many others it is a lamp on the front panel, often the operation or timer lamp, that flashes a pattern, for example a set number of blinks and then a pause.
Two things follow from this.
- The code names where the board saw a problem, not always what is broken. A fault code can point towards a sensor, a fan motor, a drain float, the communication between the two units, or the board itself. The same symptom can have a cheap cause or an expensive one, which is why the code is a starting point for a technician, not a verdict.
- The meaning depends on the brand and the model. There is no single table that is right for every aircon in Singapore. The same number of blinks can mean different things on two different makes. Be wary of any chart online that claims to decode "aircon error codes" in general, and use the one for your own model.
Step 1: record exactly what the unit is doing
Before you touch anything, spend a few minutes capturing it. This is the single most useful thing you can do, and it costs nothing.
- Photograph the display if it shows a code. Make sure the characters are readable.
- Film the blinking lamp for 20 to 30 seconds if it flashes a pattern. Counting by eye is unreliable, a short video is not. Include the whole front of the unit so the technician can see which lamp it is.
- Note which lamp and what colour. A blinking operation lamp and a blinking timer lamp are not the same signal.
- Write down when it happens. At start-up, a few minutes into cooling, only when it rains, or only when another appliance runs? A fault that appears at one particular moment is easier to trace.
- Note whether the fan still runs. Many units keep blowing air after cooling stops.
- Take a photo of the model label on the indoor unit, so the right code table can be looked up.
If the code disappears when you power the unit down, the photo or video you took is now the only record of it. That is why the order matters: record first, reset afterwards, if at all.
Step 2: the safe checks worth doing yourself
Most faults are for a technician. A few are not, and cost you only a few minutes.
- Look at the filters. Pull the front panel up and check whether the mesh is matted with dust. A badly choked filter can restrict airflow enough for the unit to shut itself down. Washing filters is something an owner can do; our post on washing the filters yourself says where that stops.
- Check the remote. Batteries, mode, timer, and whether it is accidentally set to fan only.
- Check the isolator and the breaker. An isolator that has been switched off by a cleaner or during renovation looks exactly like a dead unit.
- Look for water or ice. A unit that has iced over, or whose drain has backed up, can stop and flag a fault. Ice on the indoor unit or the pipe is covered in what to do when the indoor unit freezes over, and a drain that keeps backing up is covered in why a recurring drain choke keeps coming back.
- One reset, once. After you have recorded the signal, switching the unit off at the isolator, waiting a few minutes and switching it on again once is a reasonable way to see whether the fault was a one-off. If the same signal comes back, stop there.
What not to do
- Do not keep power-cycling it to see whether it clears. If the board is stopping the unit to protect a part, every forced restart makes the unit try again against the same fault.
- Do not reset a breaker that keeps tripping. That is a different problem, and the breaker is doing its job. See why your aircon trips the breaker.
- Do not open the casing or touch the board or wiring. The control board and the electrical connections are for a technician.
- Do not top up gas because of a code. A fault signal is not proof of low gas. Gas should be added only after the pressure has been measured, as covered in where refrigerant leaks actually happen.
- Do not ignore a burning smell, smoke or scorch marks next to the signal. If you see any of those, switch off at the isolator or the breaker and read what to do first when your aircon smells like burning.
What a code usually leads to, and what that costs
Because the code only narrows things down, the visit has to start with diagnosis. Our published price list is straightforward about how that works:
- The $45 minimum for 1 unit covers the visit and the 9-point pre-check, which is how the actual cause is identified before any work is quoted.
- A standard repair (drainage, electrical) is $80.
- Compressor and PCB replacement are quoted on-site after diagnosis. There is no fixed figure for them on the price list, so we do not give one here.
- Additional work beyond the visit is quoted before it is done.
- After-hours emergency repair calls between 10pm and 7am carry a $50 surcharge.
Those figures are the whole published picture. A blinking light does not tell anyone in advance which of the repair lines it will land on, and anyone who quotes a firm price from a photograph of a code is guessing. What a technician can honestly say is which parts to test first, and then confirm on site.
Is it worth a visit tonight?
Usually the signal alone does not make it an emergency. It is a comfort problem unless one of the safety signs above is present. If the unit is dead and the room is unbearable, the trade-off is the $50 after-hours surcharge against a few hours of sleep, and our post on what to do when your aircon stops working at night sets out how to decide. If the unit is blinking but still blows air, it can wait for a normal slot, and you can keep it off at the isolator in the meantime.
What to send the technician
The quickest way to get a useful reply is to send what the technician would ask for anyway:
- The photo of the display, or the video of the blinking lamp.
- The photo of the model label on the indoor unit.
- When it happens, and whether the fan keeps running.
- Whether it is one unit or several sharing an outdoor unit.
- Whether the breaker has tripped, and whether there is any water, ice or smell.
- Roughly how old the system is, and when it was last serviced.
If the unit has not been serviced in years, a fault code is often the unit's way of telling you it has been neglected. Our post on what to check before you call when your aircon will not turn on covers the other side of this, and what short-cycling means covers a unit that starts and stops without showing any code at all. More detail on what a repair visit involves is on our aircon repair page, and the 9-point pre-check shows what is looked at first.
Ask for the code to be explained, not just cleared
When the technician has fixed the unit, ask them what the code meant and what they found. A good answer is specific: which part, why it failed, and whether anything else nearby is worn. Our post on what your aircon technician should show you before they leave lists what to expect. A fault that is explained can be watched for. A fault that was simply reset will usually be back.
If you would like us to look at yours, WhatsApp us on 9107 2601 with the photo or video, and we will tell you what we need to check and when we can come.
Frequently asked questions
What does a blinking light on my aircon mean?
It is usually the unit reporting a fault it has detected itself. The meaning depends on the brand and model, and on which lamp is blinking and how many times, so the pattern should be recorded and matched to your model rather than guessed.
Can I decode the aircon error code myself?
Sometimes the manual for your model lists it. Even then, the code only points to the area where the unit saw a problem, not always to the part that has failed, so a technician still needs to check on site.
Is it safe to keep using the aircon with a blinking light?
If it still cools normally and there is no smell, water or breaker tripping, it is usually a comfort issue. If the unit has stopped, leave it off at the isolator rather than restarting it repeatedly.
Should I reset the aircon to clear the code?
Record the code first. After that, switching off at the isolator for a few minutes and back on once is reasonable. If the code returns, stop and have it checked.
How much does it cost to have a blinking aircon checked?
The $45 minimum for 1 unit covers the visit and the 9-point pre-check, and a standard repair (drainage, electrical) is $80. Compressor and PCB replacement are quoted on-site after diagnosis.