SiAF332111E Troubleshooting by Error Code
Part 6 Service Diagnosis 297
5.56 Open Phase
Applicable
Models
RXMQ8AR
Error Code U1
Method of Error
Detection
The phase of each phase is detected by phase detection circuit and open phase is judged.
Error Decision
Conditions
When any phase is open phase.
Supposed
Causes
Abnormal supply voltage
Open phase
Defective inverter PCB
Troubleshooting
Power supply
harness
(3-phase, 4 wires) is
properly connected to
the terminal
block.
The fuse of the noise
filter PCB is blown out.
Power supply
voltage falls within
380 V to 415 V between
L1-L2, L2-L3 and
L3-L1.
The connectors
between the terminal
block, noise filter PCB and
inverter PCB are properly
connected.
Connect the harness properly.
Replace the inverter PCB. (A3P)
Replace the noise filter PCB (A2P) and
the inverter PCB (A3P).
NO
NO
YES
YES
Check the power supply for
abnormalities.
NO
YES
Connect the connectors properly.
NO
YES
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
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