Abnormal Operation Of Thermistor For The Indoor Unit Air Inlet Temperature (Air Inlet Thermistor) - Hitachi RAS-(3-6)HVRNM2E Service Manual

8 Troubleshooting
11
Alarm code
• 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 0.24 kΩ) or cut (greater than 840 kΩ)
during the cooling process or the heating process. The system is automatically restarted when the fault is removed.
Phenomenon
Faulty air inlet thermistor
Faulty PCB
N O T E
• This data is applicable to the following thermistors:
- Indoor unit discharge air temperature
- Indoor unit liquid refrigerant temperature
- Indoor unit air inlet temperature
- Outdoor temperature
- Outdoor unit evaporating temperature
- Indoor unit gas piping
235
SMGB0064 rev.0 - 08/2011

Abnormal operation of thermistor for the indoor unit air inlet temperature (air inlet thermistor)

Cause
Fault
Incorrect connection
Check item
(Turn OFF the main switch)
Check the resistance Replace the thermistor if faulty
Check the connection
Replace PCB and
check the operation
Action
Repair the wiring and the
connections
Replace PCB if faulty 8