Hitachi RAS-2.5HVRN1 - Page 252

Alarm code
22
Abnormal operation of the thermistor for the outdoor temperature (outdoor unit ambient
thermistor) for IVX Series
• The RUN LED flickers and "ALARM" is displayed on the remote control switch.
• The unit number, the alarm code and the unit code are alternately displayed on the set temperature section.
The unit number and the alarm code are displayed on the display of the outdoor unit PCB.
– This alarm code is displayed when the thermistor is short-circuited (less than 0.2 kΩ) or cut (greater than 500 kΩ)
during the operation. However, this alarm occurs during the test run mode only. In the case that the thermistor is
abnormal during the operation, the operation continues based on the assumption that the outdoor temperature is
35 °C (cooling) / 6 °C (heating).
Is the thermistor THM7 (TA)
connected to PCB1?
Connect it
No
Outdoor
unit ambient
thermistor
Yes
Is the resistance of THM7
between 0.24 kΩ and 500 kΩ?
Faulty thermistor
No
Yes
Faulty PCB1
90
80
70
60
50
40
30
20
10
0
-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60
Thermistor resistance (kΩ)
Ambient temperature (ºC)
Thermistor characteristics
Phenomenon
Cause Check item
Action
(Turn OFF Main Switch)
Faulty thermistor for the outdoor unit
ambient
Fault Check resistance Replace thermistor if faulty
Incorrect connection Check wiring to PCB Repair wiring and connections
Faulty PCB1 Replace PCB1 and check operation Replace PCB if faulty
8 Troubleshooting
244
SMGB0060 rev. 1- 12/2010