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Daikin Air Conditioner U2 Error Code
Power supply voltage problem on Daikin air conditioners.
DaikinAll Daikin air conditioner codes
The unit saw the supply voltage drop too low, rise too high or cut out briefly. Storms, utility brownouts, a loose connection in the supply circuit or heavy equipment starting on the same circuit can all cause it.
Compatible models
Daikin lists U2 in its global and regional code tables but doesn't say which models use it. It can show on any Daikin system with an outdoor unit.
Also shown as
No other codes are listed for this fault.
Difficulty
Try the basic checks, but the usual fix is a technician's job.
Not sure you are reading the code right? See how to read Daikin air conditioner codes.
How to fix Daikin U2
Wait for stable power, then reset
If U2 showed up during a storm or brownout, wait until the power is steady, then do a breaker reset.
Note when it happens
Write down whether the code appears at start-up, when other big 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 linked to U2
These are the parts most often behind this code. Tap one to see what it does and the signs it is failing.
Order parts by your full model number so they fit.
Frequently asked questions
Which Daikin models show the U2 code?
Daikin lists U2 in its global and regional code tables but doesn't say which models use it. It can show on any Daikin system with an outdoor unit.
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.
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
Last reviewed 2026-10-19. Codes and steps can vary by model; check your owner's manual.