Why is my Daikin aircon light blinking?
A blinking operation lamp means the indoor unit has found a fault and stored an error code. On a Daikin, read the code with the wireless remote: hold the timer Cancel button for five seconds, then press it repeatedly until the unit gives one long beep. The code shows which area failed; a technician confirms the exact part.
Key takeaways
- Blinking means a stored code: the lamp tells you a fault was logged, not which part failed.
- Your remote can read it: the remote-control fault diagnosis mode finds the code in about a minute.
- The letter points to an area: A and C codes are mostly indoor, E, F, H and J codes outdoor or compressor, U codes system-wide.
- Reset once only: if the same code returns after one reset, the fault is real.
In the video above, Uncle Eric shows this checking method using nothing but the remote control. He notes that it suits Daikin's CTKC and CTKM indoor units, indoor units used in many Daikin multi-split (System 2, 3 and 4) setups.
How do I read a Daikin error code with the remote?
This works on most Daikin wireless remotes used with wall-mounted units. Button labels differ slightly between remote models.
- Stand in front of the indoor unit and point the remote at it, as you would to switch it on.
- Press and hold the timer Cancel button for about five seconds, until "00" flashes on the remote's temperature display.
- Press Cancel again, one press at a time. Each press shows the next code.
- Listen to the indoor unit after every press. Short beeps mean that code is not the fault. One long, continuous beep means the code on the display is the one the unit has stored.
- Write the code down or take a photo of the remote screen.
- To exit, hold Cancel for five seconds again, or leave the remote alone for about a minute and it returns to normal.
Take your time between presses so you can match each beep to the right code. If you go past the long beep, keep pressing: the codes cycle round again.
What do the common Daikin error codes mean?
These are Daikin's standard meanings for residential wall-mounted units. Code lists vary between series, so treat this as a guide to where the problem sits, not a diagnosis.
Code | What it points to | What to do |
|---|---|---|
00 | Normal, no fault stored | Try one reset; call us if the lamp keeps blinking |
A1 | Indoor unit PCB (circuit board) fault | Technician |
A3 | Drain water level problem (drain pump units such as cassettes) | Technician |
A5 | Freeze-up protection: the evaporator coil is too cold | Wash filters; technician if it returns |
A6 | Indoor fan motor fault | Technician |
C4 / C9 | Indoor coil thermistor / room temperature thermistor | Technician |
E1 | Outdoor unit PCB fault | Technician |
E5 / E6 | Compressor overload / compressor locked | Switch off, technician |
E7 | Outdoor fan motor fault | Technician |
F3 | Discharge pipe temperature too high | Switch off, technician |
U0 | Refrigerant shortage (low gas) | Switch off, leak check |
U4 | Communication error between indoor and outdoor units | Technician |
If your code is U0, F3, E5 or E6 and the room is getting warm, stop using the unit. Blinking right now? Message Luna on WhatsApp with the code and we will tell you the next step.
Which Daikin codes do we see most in Singapore?
A few codes come up again and again on our jobs:
- A5, freeze-up. Usually an airflow problem. Clogged filters, a dirty coil or a blower fan caked with dust stop warm room air reaching the coil, so it gets too cold and the unit protects itself. In our humidity, dust sticks to the wet coil quickly. A thorough clean such as our premium servicing with PowerJet often clears it.
- U0 and F3. These often go together with a refrigerant leak. The circuit is sealed, so low gas means a leak somewhere. Topping up without finding it only buys time; our post on aircon gas leak signs explains why.
- E7. The outdoor fan is not turning as it should, so heat cannot leave the condenser. watch: Daikin E7 error code fixed
- A3. A drain problem on cassette and ducted units, often a blocked drain or a condensate pump that has stopped. watch: Daikin SkyAir cassette A3 error fixed
- U4. Can be loose or damaged wiring between the units, a power supply problem or a board fault. It needs testing on site.
Other brands blink in their own way. For a Mitsubishi Electric example, see how we traced a blinking Starmex to a failed relay on the outdoor PCB. For how the parts behind these codes fit together, read how an aircon works and where it goes wrong.
Can I reset a blinking Daikin aircon myself?
You can try once. Read and note the code first, so you still have it if the light goes off. Then switch the aircon off at the isolator switch, wait a few minutes and switch it back on.
If the fault was a one-off, such as a brief power dip, the unit may run normally. If the same code returns, the fault is real. Resetting it over and over hides the symptom while the cause gets worse, for example a compressor running short of gas.
What it costs
The cost depends on what the code points to. We diagnose first and only replace what has failed.
Job | Price | What drives it |
|---|---|---|
Fault diagnosis visit | S$150 per visit | Flat fee per visit; parts and repair extra |
PCB replacement | Quoted after the S$150 diagnosis | Indoor or outdoor board, model, part availability |
Fan motor replacement | Quoted after the S$150 diagnosis | Indoor or outdoor motor, model |
Gas leak repair and recharge | Leak check from S$580, repair quoted after | Leak location, refrigerant type (R32 or R410A), evacuation |
When to call a technician
Call us if:
- the same code comes back after one reset
- the code points to the compressor, gas (U0, F3, E5, E6) or a circuit board
- the unit is not cooling, is leaking water, or is making new noises along with the blinking
- the code is one you cannot find, or the beeps are hard to make out
Send us the code when you get in touch; it helps us bring the right parts and tools for aircon repair and troubleshooting. You can book online in under a minute, or message Luna, our AI assistant, on WhatsApp at any hour.
Frequently asked questions
Does the remote check work on every Daikin aircon?
It works on most Daikin wall-mounted units that use the standard wireless remote. Ceiling cassettes and ducted units with a wired controller usually show the code on the controller screen instead. If your remote has no Cancel button, look up the fault diagnosis section of its manual.
Will the error code tell me exactly which part to replace?
No. The code tells you which part of the system reported the fault, not which part has failed. A sensor fault code, for example, can come from the thermistor itself, its wiring or the PCB reading it, so a technician still tests before replacing anything.
Do other brands use the same error codes as Daikin?
No. Mitsubishi Electric, Panasonic, Midea and other brands each have their own codes and checking methods, and the same letters can mean different things. Only use this list for Daikin units.
Is it safe to keep using a Daikin aircon while the light is blinking?
If the unit has stopped cooling, switch it off and leave it off until it is checked. Forcing it to restart again and again can strain the compressor, especially when the fault is low gas or a fan that is not turning.
Can I fix a Daikin error code myself?
Only the simplest cases. If the code is A5 and the filters are grey with dust, washing them may be enough. Codes that point to a PCB, sensor, fan motor, compressor or gas need a technician with the right tools.
Eric Lim, aka Uncle EricFounder of iAircon.Repair, now in its 10th year servicing aircons in Singapore. Every job is filmed, so you can watch the work on YouTube.
