Daikin error codes, explained
Daikin mini-split and light-commercial systems. Codes below: Letter-number codes (U4, A-codes…). Each guide covers what the code means, what you can safely try yourself, when to stop and call a technician, and what the repair typically costs.
Daikin U4 — Indoor/outdoor transmission (communication) error
Communication between the indoor and outdoor units failed — Daikin's equivalent of Mitsubishi's E6. Wiring faults, a power interruption to one unit, or board failure.
Try DIY first — may need a pro
Daikin A-codes — Indoor unit fault family (A3 drain, A6 fan…)
A-prefixed codes are indoor-unit faults. The one offices hit most is A3 — the drain water level system: a clogged condensate line or failed drain pump has triggered the float switch to prevent an overflow onto ceilings and desks. A6 is the indoor fan motor.
Try DIY first — may need a pro