Hitachi Set Free mini-HNRQ1 Series, Service Manual

Page: 86 / 187

79
Alarm
Code
07
Decrease in Discharge Gas Superheat
● 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 the discharge temperature of the compressor is below the estimated condensing temperature for 30
minutes during operation, the compressor stops and then the operation is automatically retried after three
minutes.If this occurs again twice in the next 120 minutes, this alarm code is displayed.
★
This alarm code is displayed when an abnormality cannot be detected by the step-out detection, caused
by locking of compressor shaft.
Is discharge thermistor
δ
THM9
ε
normal
ϋ
Is the refrigerant pipe
and electrical wiring are
connected correctly?
Is the opening ratio of the
outdoor electronic expansion
valve is less than 15%?
Whether the installation
position of the
discharge
thermistor is correct
˛
Is the electronic
expansion valve of indoor
not connected correctly?
Is the unit heating or cooling
when the failure occurs?
Avoid sudden
fluctuations in air flow
θ
such as airflow short
circuiting or thermo-ON
& OFF frequently.
Connect the valve
again.
Yes
No
Yes
Yes
Yes
No
No
Is
No
No
Yes
Yes
Replace temperature
thermistor.
Install at the correct
position.
Heating
Cooling
Whether the superheat of
discharge temperature is
less than 0 °C
ϋ
Connect the refrigerant
pipe and electrical
wiring correctly.
Whether the superheat of discharge
temperature is less than 0 °C ?
Is the outdoor electronic
expansion valve
connection correct?
Connect the outdoor
electronic expansion
valve to the right
position.
Is refrigerant
charged sufficient?
Re-charge refrigerant.
Is the refrigerant
leakage?
Repair gas leakage and
re-charge refrigerant
Check the opening of
electronic expansion
valve by the 7-
segment display.
Cooling
Heating
Is
No
Yes
Yes
Yes
Yes
Yes
No
No
No
No
TROUBLESHOOTING