SiAF332111E Troubleshooting by Error Code
Part 6 Service Diagnosis 305
5.58.3 Power Supply Insufficient or Instantaneous Abnormality (10/12 HP
Models)
Applicable
Models
RXMQ10/12AR
Error Code U2
Method of Error
Detection
Error of voltage of main circuit capacitor built in the inverter and power supply voltage.
Error Decision
Conditions
When the voltage of main circuit capacitor built in the inverter and power supply voltage is less
than 320 V.
Supposed
Causes
Power supply insufficient
Instantaneous power failure
Open phase
Defective inverter PCB
Defective outdoor unit main PCB
Defective main circuit wiring
Defective compressor
Defective fan motor
Defective connection of signal cable
Troubleshooting
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
Replace the compressor.
Replace the fan motor.
YES
Failure of
above power supply.
Check the power condition.
(1) Is the power supply voltage 380 V ±10%?
(2) Is there phase loss or wrong wiring?
(3) Is the unbalanced power voltage less than 6 V?
Repair the failure.
YES
NO
NO
NO
YES
If the motor is
seriously damaged,
it is necessary to
replace the inverter
PCB (A3P).
Go to the next page.
A
Check
if the insulation
resistance of the
compressor is less
than 100 kΩ.
Check
if the insulation
resistance of the fan
motor is less than
1 MΩ.
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