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Daikin Air Conditioner Error Codes Directory
Complete diagnostic reference for Daikin Air Conditioner fault codes. Each code includes official root causes, safety precautions, and affected replacement components.
1
Official Codes
0
DIY Checkable
U4
ElectricalHazard
Daikin AC Error Code U4: Transmission Failure Between Indoor & Outdoor Units
Communication Error (Loss of data transmission between the indoor unit PCB and the outdoor condenser unit PCB).
Top Causes:
Wiring mismatch or loose connection on terminal block 1, 2, or 3.
Blown fuse on outdoor inverter control PCB.
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