Daikin error code U2
What it means
Power supply voltage drop or main circuit overvoltage.
Possible causes
Supply voltage outside allowable range Loose or undersized supply wiring Inverter main circuit problems affecting DC bus
Suggested fix
Measure line voltage under starting and running conditions and inspect supply wiring and protection devices; correct site power issues or replace faulty inverter components after electrical testing confirms the source.
Safety first. Isolate the power supply before inspecting any unit. Refrigerant-circuit
and electrical repairs must be carried out by a qualified, registered technician.
Other Daikin codes
- A1 — Indoor PCB defect or internal failure.
- A5 — Freeze-up protection activated for the indoor heat exchanger.
- A6 — Indoor fan motor fault.
- C4 — Faulty indoor heat exchanger temperature sensor.
- C9 — Faulty indoor suction air (room) temperature sensor.
- E1 — Outdoor circuit board fault.
- E7 — Outdoor DC fan motor fault.
- F6 — High pressure control activated in cooling mode.
- U0 — Refrigerant shortage or undercharge detected.
- U4 — Transmission failure between indoor and outdoor units.