Hitachi UTOPIA RAS-4HVRP2E - Page 270

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
268
Alarm code
07
Decrease in Discharge Gas Superheat
• 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.
Ifeitherinsufcient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?
Replace temperature
thermistor
Install at the correct
position
Whether the installation position
of the discharge thermistor is
correct?
Is the unit heating or cooling
when the failure occurs?
Heating
Cooling
Whether the superheat of discharge
temperature is less than 0°C?
Whether the superheat of
discharge temperature is less
than 0°C?
Connect the refrigerant
pipe and electrical wiring
correctly
Connect the refrigerant
pipe and electrical wiring
correctly?
Is the opening ratio of the
outdoor electronic expansion
valve is less than 15%?
Connect the valve again
Is the electronic expansion
valve of indoor not connected
correctly?
Avoidsuddenuctuations
inairow,suchasairow
short circuiting or Thermo-
ON & OFF frequently
Is the outdoor electronic
expansion valve connection
correct?
Connect the outdoor
electronic expansion
valve to the right
position
Is refrigerant charged
sufcient?
Re-charge refrigerant
Is the refrigerant
leakage?
Check the opening of
electronic expansion
valve by the 7-segment
display
Repair gas leakage and re-
charge refrigerant
Yes
Yes
Cooling
Yes
Yes
Heating
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes