SiENBE34-703 Troubleshooting by Indication on the remote control
Troubleshooting 169
3.40 “U4” Malfunction of Transmission between Indoor Units
and Outdoor Units
remote control
Display
U4
Applicable
Models
AII indoor unit models
RXYSQ4~6P
Method of
Malfunction
Detection
Microcomputer checks if transmission between indoor and outdoor units is normal.
Malfunction
Decision
Conditions
When transmission is not carried out normally for a certain amount of time
Supposed
Causes
! Indoor to outdoor, outdoor to outdoor transmission wiring F1, F2 disconnection, short circuit
or wrong wiring
! Outdoor unit power supply is OFF
! System address doesn’t match
! Defect of outdoor unit PC board
! Defect of indoor unit PC board
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