Daikin R71FUV1 Service Manual page 424

Troubleshooting by Remote Controller
Remote Controller Display
U8
Applicable Models
RZ(Y)
Method of Error Detection
In case of controlling with 2- remote controller, check the
system using micro-computer if signal transmission
between indoor unit and remote controller (main and sub)
is normal.
Error Decision Conditions
Normal transmission does not continue for specified
period.
Supposed Causes
Transmission error between main remote controller
and Sub remote controller
Connection among "sub" remote controllers
Defective remote controller PCB
Si20-701_B
417