U4" Malfunction Of Transmission Between Indoor Units And Outdoor Units - Daikin R-410A Service Manual

Troubleshooting by Indication on the Remote Controller
4.38 "U4" Malfunction of Transmission between Indoor Units
and Outdoor Units
U4
Remote
Controller
Display
Applicable
AII indoor unit models
Models AII outdoor unit models
Method of Microcomputer checks if transmission between indoor and outdoor units is normal.
Malfunction
Detection
Malfunction
When transmission is not carried out normally for a certain amount of time
Decision
Conditions
! Indoor to outdoor, outdoor to outdoor transmission wiring F1, F2 disconnection, short circuit
Supposed
Causes
! Outdoor unit power supply is OFF
! System address doesn't match
! Defect of outdoor unit PC board
! Defect of indoor unit PC board
154
or wrong wiring
SiBE39-402A
Troubleshooting