Why Is My Daikin Heat Pump Flashing a Green Light?
If your Daikin heat pump's green light is flashing, the pattern tells you what's going on. Most causes are simple. One means a genuine fault.
Current Daikin residential wall units sold in NZ (FTXM, FTXV, Alira, Zena Vogue and Lite series) use an OPERATION lamp (green) and a TIMER lamp (orange) as the core pair. Higher-spec models add a MOLD PROOF lamp and a STREAMER lamp, both green, plus a wireless LAN indicator on wifi-enabled units. This guide covers wall-mounted split systems. Aura floor console units use a different multi-colour lamp system, covered briefly below. Ducted Daikin systems display faults through a wired wall controller rather than indicator lamps.
What's covered
The genuine fault pattern
If the unit stops running and the green OPERATION lamp blinks continuously on its own, that's the pattern that means a fault. Switch the unit off at the circuit breaker, and clear anything blocking the indoor or outdoor unit's air inlet or outlet while the power is off. Switch the breaker back on. Daikin's built-in safety feature holds the compressor from restarting for about 3 minutes after power returns, so don't assume the reset has failed if the unit sits quiet for a few minutes. If the green light starts blinking again once the unit tries to run, it needs a professional look.
Normal green light behaviour that isn't a fault
A few lamp states look like something's wrong but are the system working as designed. The green MOLD PROOF lamp stays lit after you turn the unit off with the remote, while the fan runs quietly at low speed to dry out the coil — this is normal and isn't the unit failing to shut down. Straight after power is restored or the unit restarts, the flaps open and close once and the motorised front panel moves to set its reference position, with airflow pausing briefly. Daikin's defrost cycle doesn't show on the lamps at all — the green light stays exactly as it was, and the only signs are the indoor fan stopping, a whistling sound from the outdoor unit, and steam or water around it, usually for 4 to 12 minutes before heating resumes on its own. On Zena Vogue models, opening the front panel manually while the unit is running stops the system immediately as a safety measure — close the panel fully, then stop and restart the unit from the remote. No technician needed.
Reading the exact fault code from the remote
Wall-mounted Daikin units don't show a numeric code on the indoor unit itself. When the green light is blinking, the exact fault code is retrieved through the remote's diagnosis function. Point the remote at the indoor unit and press and hold Cancel for about 5 seconds. The display clears and a blinking "00" appears, the normal baseline confirming no fault is active. Press Cancel repeatedly to step through the diagnostic codes — the remote gives a short beep on each step, and a continuous long beep when it reaches the active fault. The two-character code shown at that moment is the one to note down. Hold Cancel for 5 seconds to exit, or leave the remote alone for a minute and it clears on its own.
What the confirmed fault codes mean
U4 is a transmission failure between the indoor and outdoor unit — an electronic signal fault needing a technician to check wiring, terminals or boards. E7 is an outdoor fan motor fault, often caused by something physically blocking the outdoor unit's air inlet or outlet and stopping the fan from turning — clear the area and reset; if it recurs with nothing blocking it, the fan motor needs a technician. L5 is an output overcurrent, an electrical fault in the compressor's inverter module that always needs a technician. C9 is a faulty suction air temperature sensor, usually a sensor or wiring fault, though heavily restricted airflow from clogged filters can occasionally produce a false reading here, so a clean is worth ruling out first. If your remote shows a code that isn't listed here, note it down and pass it directly to your technician rather than guessing at the meaning yourself.
When flashing lights point to a maintenance issue
A dirty air filter is one of the most common reasons a Daikin unit trips into a fault state. Restricted airflow through a clogged filter is enough to stop the system and trigger the blinking green light. The same happens when the indoor or outdoor air inlet or outlet is obstructed, whether that's furniture blocking the indoor unit or debris built up against the outdoor unit. Clearing the obstruction and cleaning the filters is often enough to stop the pattern returning.
What a professional service typically finds
A unit that keeps faulting even after a clean reset usually has restricted airflow somewhere in the system that a filter clean alone hasn't reached. Dust and contamination on the internal coil, a partially blocked drain line, or a fouled outdoor unit are the common causes on residential Daikin systems. A professional service checks and clears all three, and frequently resolves fault patterns that keep coming back.
Aura floor console lamps
Daikin's Aura floor console uses a different system to wall units. A single multi-colour lamp changes colour by mode: red-blue for auto, green for dry, blue for cool, red for heat, and white for fan only. It blinks when the system needs a diagnostic check, and blinks red, blue or white for wireless LAN pairing status. A steady colour is normal operation. A blink usually means either a fault or connectivity status, but the colours work differently to the OPERATION and TIMER lamps on wall units.
Frequently asked questions
Why is my Daikin heat pump flashing a green light?
A continuously blinking green OPERATION lamp after the unit stops running means a fault, and the exact code can be read from the remote's diagnosis function. If the light is steady rather than blinking, or blinks briefly during a mode change or restart, that's normal operation.
How do I reset a Daikin heat pump showing a flashing green light?
Switch off at the circuit breaker, clear any obvious blockage from the indoor or outdoor unit, then switch the breaker back on. The compressor won't restart for about 3 minutes once power is back, which can look like the reset hasn't worked when it has. If the green light blinks again once the unit tries to run, it needs a professional.
Does my Daikin heat pump show error codes?
Not directly on the unit. Wall-mounted models signal a fault through the blinking green light, and the exact code is retrieved using the remote's diagnosis function. Hold Cancel for 5 seconds, then press Cancel repeatedly until the unit gives a long beep. The code showing at that point is the fault to note down for your technician.
What does U4 mean on a Daikin heat pump?
A transmission failure between the indoor and outdoor unit. It's an electrical communication fault that needs a technician to check wiring and connections, not something a filter clean resolves.
What does E7 mean on a Daikin heat pump?
A fault with the outdoor fan motor, usually triggered when something is physically blocking the outdoor unit's air inlet or outlet and stopping the fan from turning. Clear any obstruction around the outdoor unit first. If the code returns with nothing blocking it, the fan motor itself needs attention.
Does my Daikin heat pump show a light during defrost?
No. Daikin's defrost cycle doesn't change the lamps at all. The only signs are the indoor fan stopping and a whistling sound or steam from the outdoor unit, usually for 4 to 12 minutes before heating resumes.
What does the Mold Proof light mean on a Daikin heat pump?
It means the unit is running its automatic drying cycle after you've switched it off, keeping the fan on low speed briefly to dry out the coil. This is normal and prevents mould building up inside the unit.
Can a dirty filter cause my Daikin heat pump to fault?
Yes. Restricted airflow from a dirty filter is one of the most common triggers for the system shutting down and the green light blinking. A blocked air inlet or outlet on either the indoor or outdoor unit can trigger the same response.
What should I do if my Daikin heat pump keeps faulting after a reset?
If the green light keeps blinking after a proper breaker reset, the airflow restriction is usually deeper than a filter clean can reach. Book a professional service to check the internal coil, drain line and outdoor unit rather than resetting it repeatedly.
Does the Daikin floor console show the same lights as wall units?
No. Aura floor consoles use a single multi-colour lamp instead of separate Operation and Timer lamps. The colour changes with the mode running, and it blinks for diagnostic alerts or wireless LAN pairing rather than the patterns described above for wall units.