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Troubleshooting by Remote Controller
Si20-701_B
375
3.92
U4
or
UF
Transmission Error
(Between Indoor Unit and
Outdoor Unit)
Remote Controller Display
U4
or
UF
Applicable Models
R(Y)-FU
Method of Error Detection
Micro-computer checks if transmission between indoor
and outdoor units is normal.
Error Decision Conditions
When transmission is not carried out normally for a
certain amount of time
Supposed Causes
Wiring indoor-outdoor transmission wire is incorrect.
Defective indoor unit PCB
Defective outdoor unit PCB
External factor (Noise, etc.)