Hitachi mini-HNRQ1 Series Service Manual page 110

Alarm
55
Code
● The alarm code is flashed on the 7-segment display of the outdoor unit.
● The alarm code is displayed on the wired controller of the indoor unit.
★
When the following condition occurs three times in 30 minutes, the operation stops and this alarm code
is displayed. If this occurs less than three times in 30 minutes, the operation automatically restarts.
Condition of Activation:
1) Pre-charge failure
Main causes: AC input is under voltage, driver hardware abnormality, and so on.
2) MCU RAM abnormality
Main causes: MCU RAM abnormality, driver MCU abnormality.
3) MCU Register abnormality
Main causes: Driver MCU abnormality.
4) MCU clock abnormality
Main causes: Driver MCU abnormality, driver crystal oscillator circuit abnormality.
5) MCU FLASH abnormality
Main causes: Driver MCU abnormality.
6) Reference voltage abnormality
Main causes: Driver MCU abnormality, driver reference voltage circuit abnormality.
7) Software protection module abnormality
Main causes: Driver MCU abnormality.
Restart operation
Is the power supply voltage higher
than 80% of the rated voltage?
Is electric reactor wiring loose?
Fasten the wiring
Yes
No
Yes
No
Yes
Inverter Failure
Check the power supply voltage, remove
the fault, avoid the voltage too low or too
high.
Replace driver board.
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TROUBLESHOOTING