Daikin RXYQ-TA Series Service Manual page 294

Troubleshooting by Error Code
281
Diagnosis Flowchart-3
UA-20
Error code Sub code
Multi connection?
YES
Was the
outdoor unit PCB
replaced with a spare
PCB?
YES
Was proper setting
of spare PCB
made?
YES
Diagnosis Flowchart-4
UA-21
Error code Sub code
NO
A
NO
different model
of outdoor unit is
connected.
YES
NO
SiUS341615E
Replace the outdoor unit
(A1P).
NO
Replace the outdoor unit
(A1P).
Check for the model of outdoor
unit.
Make setting again, and then
reset the power supply.
Replace the spare PCB.
Replace the outdoor unit main PCB
(A1P).
Service Diagnosis
main PCB
main PCB