
10 Troubleshooting
Troubleshooting procedure
SMGB0091 rev.2 - 11/2015
220
Alarm code
13
Abnormal operation of the thermistor for the indoor unit heat exchanger liquid pipe
temperature (freeze protection thermistor)
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.
Is THM3 (freeze protection)
connected to the indoor unit PCB?
Connect it
No
Yes
Is the resistance of THM3
between 0.24kΩ and 840kΩ?
Faulty thermistor
No
Yes
Faulty PCB
Phenomenon
Cause
Check item
Action
(Turn OFF the main switch)
Faulty freeze protection
thermistor
Fault
Check the resistance
Replace the thermistor if faulty
Incorrect connection
Check the connection
Repair the wiring and
connections
Faulty PCB
Replace PCB and check the
operation
Replace PCB if faulty
Thermistor
resistance
(kΩ)
Air temperature (ºC)
Thermistor characteristics
Examples of position of the indoor unit freeze protection thermistor (THM3)
THM3
THM3
THM3