Hitachi UTOPIA RAS-4HVRP2E Service Manual page 270

10 Troubleshooting
Troubleshooting procedure
07
Alarm 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.
If either insufficient voltage or overvoltage is detected between the terminal R-S on the inverter PCB (Driver Board)
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 is automatically retried.
Is discharge thermistor (THM9)
normal?
Yes
Whether the installation position
of the discharge thermistor is
correct?
Yes
Is the unit heating or cooling
when the failure occurs?
Cooling
Cooling
No
Yes
Whether the superheat of
discharge temperature is less
than 0°C?
Connect the refrigerant
pipe and electrical wiring
correctly
Connect the valve again
268 SMGB0136 rev.0 - 07/2021
Decrease in Discharge Gas Superheat
Replace temperature
thermistor
No
Install at the correct
position
No
Heating
Heating
Whether the superheat of discharge
temperature is less than 0°C?
Yes
No
Connect the refrigerant
pipe and electrical wiring
correctly?
Yes
No
Is the electronic expansion
valve of indoor not connected
correctly?
Yes
No
Yes
No
Is the opening ratio of the
outdoor electronic expansion
valve is less than 15%?
Yes
Is the outdoor electronic
expansion valve connection
correct?
Yes
No
Is refrigerant charged
sufficient?
Yes
No
Is the refrigerant
leakage?
Yes
Repair gas leakage and re-
charge refrigerant
Avoid sudden fluctuations
in air flow, such as airflow
short circuiting or Thermo-
ON & OFF frequently
No
Connect the outdoor
electronic expansion
valve to the right
position
Re-charge refrigerant
Check the opening of
electronic expansion
valve by the 7-segment
display