Daikin Aurora Series Service Manual page 286

Troubleshooting by Error Code
273
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
Are all
indoor units for
VRV? (no residential
indoor units)
YES
NO
A
NO
different model
of outdoor unit is
connected.
YES
NO
NO
SiUS341802E
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.
Disconnect residential indoor units
from the system.
Replace the outdoor unit main PCB
(A1P).
Service Diagnosis
main PCB
main PCB