Daikin R71FUV1 Service Manual page 398

Troubleshooting by Remote Controller
Remote Controller Display
U4 UF
or
Applicable Models
RZQ(S)-B/C
Error Decision Conditions
The error is generated when the micro-processor detects
that the transmission between the indoor and the outdoor
unit is not normal over a certain amount of time.
Supposed Causes
Wiring indoor-outdoor transmission wire is incorrect
Defective indoor unit PCB
Defective outdoor unit PCB
Burning out fuse
Defective fan motor
External factor (Noise, etc.)
Si20-701_B
391