Quick answer: The Daikin A3 error code is a drain alarm. Daikin calls it “Drain Level Control System Abnormality”: water in the indoor unit’s drain pan has risen too high. Daikin lists a clogged or upward-sloping drain, a faulty drain pump or a faulty float switch as causes. Write the code down, switch the system off and call a technician.
Written by Ofek Shamir, owner of The Guys Group · Updated 29 September 2026 · Sources: Daikin manuals and fault tables, linked below.
What does A3 mean on my Daikin ducted aircon?
A3 means your Daikin’s drain level control system has tripped. Daikin’s fault table names the code “Drain Level Control System Abnormality” and lists three causes: “Drain clogging, upward slope, etc.”, a “Defective drain pump”, and a “Defective float switch or short circuit connector”.
When your system cools, it makes condensation water that runs out through the indoor unit’s drain piping. Daikin’s Australian ducted manual says that during cooling “water should drip from the outlet of the indoor unit’s drain piping”, and adds: “If you think the drain is blocked stop the air conditioner and contact your installer.”
How do I see the error code on my Daikin controller?
On most Daikin wired controllers, the operation light blinks when a fault stops the system, and the screen tells you how to see the code. Daikin Australia says the message reads “Error: Push Menu button”; press the Menu button and the code appears. On older controllers such as the BRC1C62, Daikin says the light blinks “and a malfunction code is displayed” straight away.
If your system has a Daikin wireless remote, Daikin’s instructions are to hold the timer cancel button for 5 seconds while pointing the remote at the indoor unit. This only shows the code. It does not clear the fault.
Write down the code and your indoor unit’s model. Daikin’s code list covers several ranges (RA, SkyAir, VRV and others), so your technician will confirm what the code means on your model.
What do the other Daikin error codes mean?
Each Daikin code points to one part of the system, and most need a technician. The table below takes Daikin’s own names and causes directly from its “Simple Self-Diagnosis by Malfunction Code” table. The owner checks come from Daikin’s manuals. In the table, a thermistor is a temperature sensor, a PCB is a circuit board and HPS is the high pressure switch.
| Code | What Daikin calls it | Causes Daikin lists | What you can do |
|---|---|---|---|
| A3 | Drain Level Control System Abnormality | Drain clogging or upward slope, defective drain pump, defective float switch | Switch off, call a technician |
| A5 | High pressure control in heating, freeze-up protection control in cooling | Clogged indoor air filter, faulty heat exchanger thermistor | Check the return air filter, then call a technician if it returns |
| A6 | Malfunction of fan motor | Fan motor wiring, defective fan motor, defective indoor unit PCB | Call a technician |
| C4 | Malfunction of liquid pipe thermistor for heat exchanger | Defective thermistor, indoor unit PCB or connector | Call a technician |
| E3 | Actuation of high pressure switch (HPS) | Dirty outdoor unit heat exchanger, defective switch, clogged refrigerant piping, connector | Keep the outdoor unit clear, call a technician |
| U0 | Shortage of refrigerant | Refrigerant shortage or clogging, defective thermistor, low pressure sensor or outdoor PCB | Call a technician |
| U4 | Malfunction of transmission between indoor and outdoor unit | Wiring between the units, outdoor unit power off, address mismatch, indoor or outdoor PCB | Call a technician |
Using another brand? See our guides to Mitsubishi P5, P6 and PA error codes, LG CH04 and CH61 error codes, and ducted aircon error codes for other brands.
Can I reset a Daikin error code myself?
No. Daikin gives owners no reset for fault codes, and its owner manuals do not give a button sequence that fixes one. Its Australian ducted manual says that if a two-digit code appears, “Write down the fault code and then stop the operation”, then “Notify your Daikin dealer and inform him/her of the display.” The code is there to tell the repairer “what the problem may be”.
The same manual also says:
- After a power failure, the system “may automatically restart immediately after the power supply recovers”.
- If the fuse has blown or the circuit breaker has tripped: “Please contact and notify qualified technicians to check.”
Daikin controllers keep a malfunction history your technician can read. Leave it alone so they can see what happened.
Is it safe to keep running my Daikin with an A3 error?
No. Daikin’s Australian ducted manual says to stop the system when a fault code appears, and if water leaks from anywhere other than the drain pipe, its instruction is simply: “Stop the operation.” The code has already stopped the system for a reason, so do not keep restarting it.
Do not open the unit yourself. The manual says: “NO USER SERVICEABLE PARTS ARE INSIDE THE AIR CONDITIONER. DO NOT REMOVE ANY ACCESS PANELS OR FIXED COVERS.” If you smell burning, Daikin says to “switch off the main switch” and contact your dealer.
Why does my Daikin A3 error keep coming back?
A3 keeps coming back because the cause is still there. Switching the system off and on does not clear a clogged drain, a failed drain pump or a faulty float switch, so the system sees the same problem again and stops again. Each cause needs a technician to find and fix it.
Daikin’s FBA ducted guide puts “Clean the drain pan so that it does NOT become clogged and dusty” in its maintenance section for an authorised installer or service agent, not the owner.
What does A5 mean on a Daikin? Is it a dirty filter?
A5 means the indoor coil has hit a temperature limit, and a dirty filter is one of the two causes Daikin lists. Daikin’s name for it is “High pressure control in heating, freeze-up protection control in cooling”, and the causes are “Clogged air filter of indoor unit and short circuit” and a “Defect of indoor unit heat exchanger thermistor”.
Daikin’s Australian ducted manual explains why the filter matters: “Dirt and dust caught in the air filter causes a drop in airflow, which leads to a decline in performance.” If the system stops after running for a while, it says to “Check if the air filter is clogged. Clean the air filter(s).” Daikin also advises cleaning filters at the start of summer and winter, and “Once every 2 weeks” in dusty locations.
Clean the return air filter as your manual describes, and do not run the system without it: Daikin warns this “will allow dust to enter the indoor unit and build up on the heat exchanger coil and fan motor”. If A5 comes back with a clean filter, call a technician to check the thermistor and the rest of the system.
What does E3 mean on a Daikin?
E3 is an outdoor unit code. Daikin calls it “Actuation of high pressure switch (HPS)”, and lists a “Dirty outdoor unit heat exchanger”, a defective high pressure switch, clogged refrigerant piping and a connector problem as causes. Only a technician can tell which one it is.
What you can do: Daikin’s manual says to check “if the air inlet or outlet of outdoor or indoor unit is blocked by obstacles” and to “Remove the obstacle and make it well-ventilated.” Then write down the code and call a technician.
What does U4 mean on my Daikin after a storm or power cut?
U4 means the indoor and outdoor units have stopped talking to each other. Daikin calls it “Malfunction of transmission between indoor and outdoor unit”, and its causes include faulty or wrong wiring between the units, “Outdoor unit power supply is OFF”, a system address mismatch, and a defective indoor or outdoor circuit board.
Because power to the outdoor unit being off is on Daikin’s list, a power problem can be behind U4. If a fuse has blown or a breaker has tripped, Daikin’s manual says to have qualified technicians check it. The other causes, wiring and circuit boards, are also technician work. If the main power has been off for a long time, Daikin’s manual says to turn it back on “6 hours before restarting operation”.
What does U0 mean on a Daikin? Does it need gas?
U0 is Daikin’s “Shortage of refrigerant” code, but low gas is not the only cause. Daikin also lists refrigerant clogging, a defective thermistor, a defective low pressure sensor and a defective outdoor unit main PCB. Only a technician can test which of these it is, so do not assume it just needs gas.
What does “Time to clean filter” mean on my Daikin controller?
“Time to clean filter” is a reminder, not a fault. Daikin’s wired controllers, such as the BRC1E and the Madoka (BRC1H), show it after a set number of running hours, and Daikin’s Australian ducted manual says that when the display shows the filter message, “clean the filter(s)”.
The reminder is a timer. It does not measure the filter, and on the Madoka the installer can change the interval or turn the filter sign off, so a controller that never shows the message is not proof of a clean filter.
When should I call someone, and who?
Error codes like A3, U4 or U0 need a qualified air conditioning technician. If your filter reminder is on, the return air filter is caked with dust or the system just hasn’t been cleaned in a while, The AC Cleaning Guys can help. Our ducted system clean is $349 + GST and includes a new filter, cleaning of the aluminium duct foils from the filter through to the return duct, a professional sanitise, and an airflow check and test run, with no mess left behind. If you prefer to keep your current filter, our Deep Scrub & Sanitise option is $229 + GST: the duct foils deep-scrubbed through to the return duct, a professional sanitise, and an airflow check and test run. See our ducted aircon cleaning service or call 1300 380 090.
The AC Cleaning Guys is an independent cleaning company, not affiliated with or authorised by Daikin.
Sources
- Simple Self-Diagnosis by Malfunction Code (SM-TS3), Daikin
- How to check error codes (SM-TS3), Daikin
- FDYAN / FDYUAN ducted operation manual, Daikin Australia
- Understanding symbols on Daikin controllers, Daikin Australia
- FBA-A ducted unit user reference guide, Daikin
- BRC1E53 wired controller user reference guide, Daikin
- BRC1H Madoka installer and user reference guide, Daikin
