Hitachi UTOPIA RAS-4HVRP2E - Page 296

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
294
Alarm code
55
Inverter Failure
• Thealarmcodeisashed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.
Yes
Yes
Yes
No
No
Restart operation
Is the power supply voltage higher than 80%
of the rated voltage?
Is electric reactor wiring loose?
Fasten the wiring
Check the power supply voltage, remove the fault,
avoid the voltage too low or too high
Replace driver board