Daikin REYQ-AATJA, Service Manual, Page: 398 / 495

Troubleshooting by Error Code SiUS372201EA
391 Part 6 Service Diagnosis
3.65 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 190 VDC
(for 208/230 V models) or 380 VDC (for 460 V models).
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
There are
some defects in the
power supply conditions
aforementioned.
The insulation
resistance of the
compressor is less than
100 k .
NO
YES
YES
Fix the defects.
Replace the compressor.
Check for power supply
conditions.
(1) Power supply voltage falls
within ±10% of the rated
voltage?
(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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