Hitachi FSG Series Service Manual page 49

Alarm Code
22
n "RUN" light flickers and "ALARM" is indicated on the remote control switch.
n The unit No., alarm code and the unit code is alternately indicated on the set temperature section, and the
unit No. and alarm code are indicated on the display of the outdoor unit PCB.
‘
This alarm code is indicated when the thermistor is short-circuited (less than 0.2 kW) or cut (greater than
500 kW) during running. However, this alarm occurs during test running mode only. In the case that the
thermistor is abnormal during running, operation continues based on the assumption that the outdoor
temperature, is 35 °C (Cooling) / 6 °C (Heating).
Is it connected to THM7 (TA)
of PCB1.
Yes
Is resistance of THM7
between 0.24kW and 500kW?
Yes
Faulty PCB1
Phenomenon
Faulty
Thermistor for
Outdoor Unit
Ambient
Faulty PCB
Abnormality of Thermistor for Outdoor Air Temperature
(Outdoor Unit Ambient Thermistor)
No
Connect it.
No
Faulty Thermistor
Refer to page 1-34 for
thermistor resistance
.
Cause
Fault
Incorrect Connection
TROUBLESHOOTING
Check Item
Check resistance.
Check wiring to PCB.
Replace PCB and Check
operation
1
41
Outdoor Unit
Ambient
Thermistor
(THM7)
Action
(Turn OFF main switch)
Replace thermistor if
faulty.
Repair wiring and
connections.
Replace PCB if faulty