SiAF332111E Troubleshooting by Error Code
Part 6 Service Diagnosis 301
5.58.2 Power Supply Insufficient or Instantaneous Abnormality (6/8 HP
Models)
Applicable
Models
RXMQ6/8AR
Error Code U2
Method of Error
Detection
Detect the voltage of capacitor of the main circuit in the outdoor unit main PCB.
Error Decision
Conditions
When the voltage in the DC circuit (between diode module and power module) falls below
220-240 VDC (RXMQ6AR) or 380 VDC (RXMQ8AR).
Supposed
Causes
Abnormal power supply voltage
Instantaneous power failure
Open phase
Defective inverter PCB (RXMQ8AR)
Defective outdoor unit main PCB
Defective compressor
Defective main circuit wiring
Defective fan motor
Defective connection of signal cable
Troubleshooting RXMQ6AR
There are some
defects in the power
supply conditions
aforementioned.
The insulation
resistance of the
compressor is less than
100 k.
NO
YES
YES
Remedy the defects.
Replace the compressor
(M1C).
Check for power supply
conditions.
Check if power supply voltage
falls within the range of
220-240 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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