Fujitsu WATERSTAGE 112 Maintenance Document page 35

Heat Pump, Split System, Single Service, 3 phase
Clear 12: Heat-exchange thermistor (intermediate) error
Hydraulic Unit LED: Green 7 flashes / Red 3 flashes
Outdoor Unit LED: 5 flashes
Probable causes:
•
Misconnection.
•
Sensor failure.
•
Main PCB failure.
Check:
1. Check the sensor connection:
See if the connector has been disconnected.
-
See if the connection is correct.
-
Check for any damage on the sensor cable.
-
After solving the misconnection problem, switch the heat pump back on.
2. Remove the sensor and check its resistance value :
- Check the resistance value
Temperature (°C)
Resistance (kΩ) 27,5 20,9 16,1 12,4 9,73 7,67 6,10 3,95
- If the thermistor is faulty, replace it.
3. Check the electronic board voltage:
- Make sure circuit diagram of outdoor unit and check terminal voltage at thermistor (DC5.0V)
- If there is no voltage, replace Main PCB.
Maintenance Document 1394-1
OK
-10 -5 0 10
OK
15 20 25 30
35