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Daikin Air Conditioner U2 Error Code
Power supply voltage problem. Here is what it means and how to clear it, easiest fix first.
The unit detected that the supply voltage dropped too low, rose too high, or briefly cut out. Storms, utility brownouts, a loose connection in the supply circuit or large equipment starting on the same circuit can all cause it.
Daikin uses this code across its residential split, SkyAir and VRV ranges, but the exact meaning and causes can vary by series, model year and region, so confirm it in your unit's manual. How to read it: most Daikin ductless wall units only blink the operation lamp. On remotes such as the ARC433 series, press and hold the timer Cancel button for roughly 5 seconds until 00 blinks on the screen, then press Cancel again one step at a time; when the indoor unit answers with a long continuous beep, the code showing is the stored fault. SkyAir and VRV wireless remotes use a different sequence with the Inspection/Test, up/down and MODE buttons, and wired wall controllers usually show the code on their screen.
How to fix Daikin U2
Reset the power at the breaker
Switch the system off with the remote, then turn off its circuit breaker in your home's main panel. Wait about 5 minutes, switch the breaker back on and restart the unit. If U2 appeared during a storm or brownout, wait until power is stable before restarting.
Note when it happens
Write down whether the code appears at start-up, when other large appliances run, or at random. That pattern helps an electrician or HVAC technician find the cause quickly.
When to call a technician
If U2 keeps returning on stable utility power, have an electrician or HVAC technician check the supply voltage and connections. Don't open the outdoor disconnect box or the unit's electrical panel.
Parts that commonly cause U2
- supply wiring
- outdoor control board
Order parts by your exact model number so they fit.
Other Daikin air conditioner codes
- U4Indoor and outdoor units can't communicate
- U0Low refrigerant or restricted refrigerant flow
- UAIndoor and outdoor units don't match
- A1Indoor unit control board fault
- A3Condensate water level too high
- A5Freeze-up or overheat protection
- A6Indoor fan motor fault
- C4Indoor coil temperature sensor fault
- C9Indoor room air temperature sensor fault
- E1Outdoor unit control board fault
- E5Compressor overload or lock-up protection
- E6Compressor won't start
- E7Outdoor fan motor fault
- E8Compressor current too high
- F3Compressor discharge temperature too high
- F6High pressure in cooling mode
- H6Compressor position sensing error
- L4Inverter heat sink overheating
- L5Inverter output overcurrent
Frequently asked questions
What does U2 mean on a Daikin air conditioner?
The unit detected that the supply voltage dropped too low, rose too high, or briefly cut out. Storms, utility brownouts, a loose connection in the supply circuit or large equipment starting on the same circuit can all cause it.
Can I fix Daikin U2 myself?
Only the basic checks. You can safely try the steps above, but U2 usually points to a part or fault that needs a technician.
What if U2 keeps coming back?
A code that returns after a reset and the checks above usually means a part is wearing out. Note when U2 appears (which cycle, how often) and have your model number ready; it helps a technician bring the right part on the first visit.
Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.