Hitachi RAS-(4-12)HNP(1)(E) - Abnormal Operation of the Thermistor for the Outdoor Temperature (Outdoor Unit Ambient Thermistor)

8 Troubleshooting
249
SMGB0087 rev.0 - 12/2013
8
Alarm code
22
Abnormal operation of the thermistor for the outdoor temperature (outdoor unit ambient thermistor)
• The RUN LED ickers 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.
Is the thermistor (THM7: red)
connected to PCB1?
Connect it
No
Yes
Is the resistance of THM7
between 0.24kΩ and 500kΩ?
Faulty thermistor
No
Yes
Faulty PCB1
Outdoor temperature thermistor
RAS-2/2.5HVNP
RAS-3HVNC
Outdoor temperature thermistor
Other than above
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
74
43
33
26
20
16
12.5
10
8
5.3
3.6
2.5
56
Ambient temperature (ºC)
Thermistor characteristics
Thermistor resistance (kΩ)
Phenomenon Cause Check item
Action
(Turn OFF Main Switch)
Faulty thermistor for the out-
door 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