Daikin VRV X RXQ6-48ANR Series, Service Manual, Page: 243 / 297

SiME341909EA Troubleshooting by Error Code
Part 6 Service Diagnosis 237
5.51 Power Supply Insufficient or Instantaneous Abnormality
Applicable
Models
All outdoor unit models
Error Code
U2
Method of Error
Detection
Detect the voltage of capacitor of the main circuit in the inverter PCB.
Error Decision
Conditions
When the voltage in the DC circuit (between diode module and power module) falls below
380 VDC.
Supposed
Causes
 Abnormal power supply voltage
 Instantaneous power failure
 Open phase
 Defective inverter PCB
 Defective outdoor unit main PCB
 Defective compressor
 Defective main circuit wiring
 Defective fan motor
 Defective connection of signal cable
Troubleshooting
Check in Monitor Mode
For the models equipped with 2
compressors, check the
compressor M1C or M2C
applicable to the error code
U2
while in monitor mode of the
outdoor unit.
There are some
defects in the power
supply conditions
aforementioned.
The insulation
resistance of the
compressor is not more
than 100 k
Ω
.
NO
YES
YES
Remedy the defects.
Replace the compressor.
RXQ6-12AR: M1C
RXQ14/16AR: M1C, M2C
Check for power supply
conditions.
(1) Power supply voltage falls
within the range of 380 to
415 V?
(2) Any open phase in the
power supply wiring or
any wrong wiring?
(3) Imbalance in the power
supply voltage is
maintained within 12 V?
A
NO
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
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