Fujitsu WATERSTAGE 112 Maintenance Document page 32

Heat Pump, Split System, Single Service, 3 phase
Clear 9: Outdoor temperature thermistor error
Hydraulic Unit LED: Green 7 flashes / Red 4 flashes
Outdoor Unit LED: 7 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) 115 62,3 46,6 35,2 26,9 20,7 16,1 12,6 7,97 5,18 3,45 2,36 1,65
- 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.
32
OK
-20 -10 -5 0
OK
5 10 15 20 30 40 50 60
Maintenance Document 1394-1
70