Hitachi FS3 Series, Service Manual

Page: 49 / 240

1
TROUBLESHOOTING
41
Alarm Code
22
Abnormality of Thermistor for Outdoor Air Temperature
(Outdoor Unit Ambient Thermistor)
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 k
W
) or cut (greater than
500 k
W
) 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.
No
Connect it.
Yes
Is resistance of THM7
between 0.24k
W
and 500k
W
?
No
Faulty Thermistor
Yes
Refer to page 1-34 for
thermistor resistance
Faulty PCB1 .
Phenomenon Cause Check Item
Action
(Turn OFF main switch)
Fault Check resistance.
Replace thermistor if
faulty.
Faulty
Thermistor for
Outdoor Unit
Ambient
Incorrect Connection Check wiring to PCB.
Repair wiring and
connections.
Faulty PCB
Replace PCB and Check
operation
Replace PCB if faulty
Outdoor Unit
Ambient
Thermistor
(THM7)