Power Supply Insufficient Or Instantaneous Abnormality - Daikin REYQ-TA Series Service Manual

Troubleshooting by Error Code

3.54 Power Supply Insufficient or Instantaneous Abnormality

U2
Error Code
Applicable
All outdoor unit models
Models
Method of Error
Detect the voltage of capacitor of the main circuit in the inverter PCB.
Detection
Error Decision When the voltage in the DC circuit (between diode module and power module) falls below 380VDC.
Conditions
Supposed
Causes
Troubleshooting
249
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
Be sure to turn off the power switch before connecting or disconnecting
Caution connectors, or parts may be damaged.
Check in Monitor Mode
8-14 ton classes are equipped
with 2 compressors.
Check for the compressor 1 or 2
applicable to the error code U2
while in monitor mode of the
outdoor unit PCB.
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?
There are
some defects in the
power supply conditions
aforementioned.
NO
The insulation
resistance of the
compressor is not more
than 100 kΩ.
NO
A
YES
YES
SiUS371614E
Remedy the defects.
Replace the compressor.
REYQ72TA: M1C
REYQ96-168TA: M1C, M2C
Service Diagnosis