Fujitsu WATERSTAGE 112 Maintenance Document page 36

Heat Pump, Split System, Single Service, 3 phase
Clear 13: Heat sink thermistor (P.F.C.) error
Hydraulic Unit LED: Green 7 flashes / Red 7 flashes
Outdoor Unit LED: 10 flashes
Probable causes:
•
Misconnection.
•
Sensor failure.
•
Main PCB failure.
Check:
1. Check the sensor connection:
See if the connector has been removed
-
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) 15,8 12,2 9,5
Temperature (°C) 60
1,17 0,83 0,60 0,44 0,33 0,25 0,19
Resistance (kΩ)
- 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.
36
OK
0 5 10 15
7,5
100 110 120
70 80 90
OK
20 30 40 50
5,9 3,78 2,50 1,69
Maintenance Document 1394-1