Daikin Aurora Series Service Manual page 268

Troubleshooting by Error Code
2.57.2 Reverse Phase, Open Phase (RXLQ72TAYDU)
U1
Error Code
Applicable
RXLQ72TAYDU
Models
Method of Error The phase of each phase are detected by reverse phase detection circuit and right phase or
Detection reverse phase are judged.
Error Decision When a power supply is reverse phase, or T phase is open phase.
Conditions
Supposed
Causes
Troubleshooting
255
Power supply reverse phase
T phase open phase
Defective outdoor unit main PCB (A1P)
Be sure to turn off the power switch before connecting or disconnecting
Caution connectors, or parts may be damaged.
There
is an open
phase at the power
supply (T phase) terminal
section (X1M) of the
outdoor unit.
NO
Operation
is normal if one
phase of power supply
line phase is
replaced.
NO
Faulty wiring or
wiring disconnection
between the outdoor unit
main PCB (A1P) and the
open phase
protection PCB
(A10P)?
NO
YES
YES
YES
SiUS341802E
Fix the open phase. Requires
inspection of field power supply
section.
Reverse phase.
Countermeasure of the problem is
completed by phase replacement.
Correct the falty wiring or the
wiring disconnection.
Replace the outdoor unit main
PCB (A1P).
Service Diagnosis