Five manufacturers, five ways to show a fault: a blinking lamp, a code on the remote, a count of flashes. How to read each one, what the common codes mean, and the displays that are not faults, all from the manufacturers' own documents.
Five brands, five ways to show a fault
An inverter air conditioner watches itself: sensors on both units feed a controller that stops the system and records a code when a reading goes out of range. The code is written for the technician. What you can do is read it, write it down and pass it on, and the manufacturers' documents say exactly that.
How the code reaches you differs by brand, which is why a search for a code so often lands on the wrong brand's list. From the documents on our manuals and brochures page and the manufacturers' own service references:
- Mitsubishi Electric wall splits show no code: the operation indicator lamp blinks. The ducted units show one on the wired controller.
- Panasonic wall splits blink the TIMER indicator; the remote retrieves the code.
- Daikin wall splits put the code on the remote's temperature display after a five-second press of the timer cancel button.
- Fujitsu General wall splits flash the operation and timer lamps a set number of times each.
- ActronAir wall splits show the code on the unit and flash the operation lamp; the ducted controllers show it on screen.
Mitsubishi Electric: a blinking lamp, or a code on the ducted controller
The MSZ-AP, MSZ-EF and MSZ-LN user manuals on our downloads page carry no code table. Their instruction sits under "when you think that trouble has occurred": stop using the air conditioner and consult your dealer when the operation indicator lamp blinks.
Ducted is different. The PEA, PEAD and Large Capacity units run from a wired controller, and the PEAD installation manual carries the check code table. The codes a homeowner is most likely to meet:
- P1, P2, P9: intake or pipe sensor error
- P4 and P5: drain sensor error, drain pump error
- P6: freezing or overheating safeguard operation
- E6, E7, EE: communication error between the indoor and outdoor units
- U2: abnormal high discharge temperature or insufficient refrigerant
One display is not a fault: PLEASE WAIT for about three minutes after the power comes on, while the system runs its initial settings. The user manuals say to wait.
When a code does appear, the same manuals say the protection devices have operated: turn the power switch off, consult your dealer with the model name and what the controller showed, and do not attempt a repair.
Panasonic: the TIMER light blinks, the remote reads the code
Panasonic's Z Series operating instructions give the retrieval in four steps. If the unit stops and the TIMER indicator blinks, hold the CHECK button on the remote for five seconds, then press the TIMER up or down button until the unit beeps, and write down the code on the display.
Hold CHECK for five seconds again to leave the check, then turn the unit off and give the code to your dealer.
The document lists 54 codes, 40 beginning with H and 14 with F. The H codes are mostly sensor and communication faults, the F codes are protection trips. The ones that turn up at home:
- H11: indoor and outdoor units not communicating
- H14, H23, H24, H27, H28: an indoor or outdoor temperature sensor abnormality
- H21: the indoor float switch has operated, which is a drain problem
- H99: freeze protection on the indoor coil; the manual's cleaning section says a dirty unit can bring it on
- F91: refrigeration cycle abnormality
- F95 and F97: high pressure and compressor overheating protection
Two blinks are not faults. The POWER indicator blinks before a timed start and during defrost in heating, and the manual lists both under symptoms that do not indicate malfunction.
Daikin: hold timer cancel for five seconds
Daikin's after-sales service reference, Simple Self-Diagnosis by Malfunction Code, gives the room air conditioner procedure. Point the remote at the indoor unit and hold the timer cancel button for five seconds: "00" flashes in the temperature display. Press the button repeatedly and the display steps through the codes.
A short beep means no match; the code showing when you hear the long beep is the fault. For ducted systems on the BRC1E wired controller, "Error: Press Menu Button" appears at the bottom of the screen, and the Menu/Enter button shows the code.
The letter is the area. A and C are the indoor unit, E, F, H and J the outdoor unit, L and P the inverter, and U the system between them. From the sequence the wireless remote steps through:
- U4: transmission between the indoor and outdoor unit
- A3: drain level control system abnormality
- A5: high pressure control in heating, freeze-up protection in cooling
- C4, C9: indoor heat exchanger or suction air thermistor
- E5, E6: compressor motor overheat or overcurrent
- U0: shortage of refrigerant
- U2: power supply malfunction or instantaneous power failure
Fujitsu General: count the flashes
Fujitsu General's wall splits report through the lamps on the indoor unit. The manufacturer's error code reference, which its Australian support site names as the authoritative source, gives the pattern for the ASTG09, 12 and 18 LVCA wall units: the operation lamp's flash count is the fault group and the timer lamp's flash count is the detail within it.
- operation lamp off, timer 2 to 5 flashes: serial signal error between the indoor and outdoor units
- 2 flashes: indoor unit thermistor (timer 2 the room air, 3 the heat exchanger)
- 3 flashes: outdoor unit thermistor (timer 2 discharge, 3 heat exchanger, 4 outdoor air)
- 6 flashes: indoor fan motor (timer 2 locked, 3 abnormal rotation)
- 7 flashes: refrigerant cycle (timer 2 discharge temperature, 3 cooling high pressure)
- every lamp blinking together: model error
The pattern repeats, so count each lamp through a full round before writing it down. Larger wall units in the same document use higher counts, 8 to 13 on the operation lamp.
ActronAir: a code on the unit, a longer list on the ducted controllers
ActronAir publishes one error code document for its whole range, Doc. 9590-0000-05, version 12 of January 2026, and its instruction is the same on every page. If the problem persists after the checks, turn the unit off immediately and contact ActronAir Service with a description of the fault and the model number.
The Serene wall split shows a code and flashes the operation lamp to match:
- E1 (2 flashes): communication error between the indoor and outdoor units
- E3 (4 flashes): indoor fan speed out of control
- E4, E5 (5 and 6 flashes): room or coil temperature sensor open or short circuit
- EC (7 flashes): refrigerant leakage detection
- P0, P1, P2, P4: inverter and voltage protection, compressor drive error
The 19 kW and larger Advance ducted systems in our range report through the NEO or LR7 wall controller with a numbered list:
- E3 and E4: the room and coil sensors
- E9 and E11: the low and high pressure switches tripping
- E26 to E29: current and voltage limits
- E51: indoor to outdoor communication
The same document lists displays that are status, not faults: boot for 30 seconds at power-up, dEF during defrost, oiLr for oil return, and dr-1 to dr-3 during a demand response event. It also notes that a fault may not show on the wall controller until it has occurred several times.
What to do with the code
Every manual above ends the same way. Mitsubishi Electric: turn off the power switch and consult your dealer with the model name and the display. Panasonic: turn the unit off and inform the code to an authorised dealer. ActronAir: turn the unit off and contact service with the model number. None of the codes is a repair you do yourself.
So the useful things to have ready when you book a repair are the brand, the model name from the label on the indoor unit, the code or the flash counts, and what the unit was doing when it stopped. A photo of the display or the lamps with your quote request lets us read the code before the visit.
If there is no code, only weak or warm air, what we check when an air conditioner is not cooling covers the order of the checks, and a leaking indoor unit has its own guide.
Sources
- Mitsubishi Electric PEAD ducted installation manual (the check code table), the PEA, PEAD and Large Capacity ducted user manuals (the error display and PLEASE WAIT) and the MSZ-AP, MSZ-EF and MSZ-LN user manuals (the operation indicator lamp), all on our manuals and brochures page
- Panasonic Z Series operating instructions, on the same page: the retrieval procedure, the 54-code table, the symptoms that do not indicate malfunction, the H99 cleaning note
- Daikin Industries After Sales Service Division, Simple Self-Diagnosis by Malfunction Code, SM-TS3 (the code matrix) and Self-Diagnosis by Remote Controller (the timer cancel procedure and the code sequence), both linked from Daikin's error codes page
- Fujitsu General Australia, Legacy Error Codes and Diagnostic Reference, updated 5 August 2026, and its attached error code reference of August 2015: the wall-mounted lamp patterns
- ActronAir Error Codes, Doc. 9590-0000-05 Ver. 12, 29 January 2026: the Serene and Advance tables, the status codes and the service instruction
- Our catalogue under split systems and ducted systems: the series each document covers, 29 August 2026