What it means
Daikin's US service manual calls it low-voltage or over-voltage detection and says the compressor restarts on its own after a 3-minute standby. Daikin's global list words it as a power supply fault or instantaneous power failure.
What to check, in order
- Wait a few minutes
Daikin's service manual says the compressor restarts automatically after a 3-minute standby.
- Check for a power cut or tripped breaker
Daikin's troubleshooting page says to check whether a breaker has tripped, a fuse has blown or there has been a power cut.
- Reset at the breaker
If the code stays, switch off the air conditioner's own breaker for 20 minutes, then switch on and restart with the remote.
When to call an engineer
If it keeps coming back, Daikin's service manual lists supply voltage out of specification, momentary voltage drops or power failures, electrical noise, a disconnected compressor harness, a shorted fan motor winding and faulty voltage detection circuits or control boards. An electrician can check the supply, and an air conditioning engineer or HVAC technician the unit.
Quick answers
What does the Daikin U2 error code mean?
The control board has seen the power supply voltage drop too low or rise too high, for example during a brief dip or power cut, and has stopped the compressor. Daikin's US service manual calls it low-voltage or over-voltage detection and says the compressor restarts on its own after a 3-minute standby. Daikin's global list words it as a power supply fault or instantaneous power failure.
Can I fix Daikin U2 myself?
Easy (about 25 minutes). Start with: wait a few minutes; check for a power cut or tripped breaker; reset at the breaker. If it keeps coming back, Daikin's service manual lists supply voltage out of specification, momentary voltage drops or power failures, electrical noise, a disconnected compressor harness, a shorted fan motor winding and faulty voltage detection circuits or control boards. An electrician can check the supply, and an air conditioning engineer or HVAC technician the unit.
Is Daikin U2 worth repairing?
Usually free. A one-off after a power blip usually clears by itself. If it repeats, the supply or a board needs checking.
Checked against
- Daikin Service Manual SiUS042113E, FTXM-V / RXM-V inverter pair wall mounted type (manualslib copy of the Daikin PDF)
- Daikin Service Manual SiUS04-924_A, RXS / FTXS H-series inverter pair wall mounted type (PDF)
- Daikin: Simple Self-Diagnosis by Malfunction Code, SM-TS3, list of error codes (PDF)
- Daikin Global: Troubleshooting, split and multi-split air conditioners
Last reviewed October 2026. Manufacturers update their pages, and your manual is the final word. Spotted a mistake? Email contact@appliance-error-codes.com.