Fujitsu Waterstage WS G140DC6 Series Maintenance Document page 18

Split system (Single phase and 3-phase type)
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)
THERMISTOR
(COMPRESSOR)
THERMISTOR
(OUTDOOR)
THERMISTOR
(PIPE)
THERMISTOR
(DISCHARGE)
THERMISTOR
(HEAT SINK)
THERMISTOR
(PIPE MID)
THERMISTOR
(EXPANSION)
- If there is no voltage, replace Main PCB.
18
OK
-10 -5 0 10
OK
15 20 25 30
Maintenance Document 1544-1