Fujitsu Comfort Series Service Manual page 26

Troubleshooting 5
HYDRAULIC UNIT Error Method:
Hydraulic unit Heat Exchanger
Thermistor Error
Detective Actuators:
Hydraulic unit interface PCB Circuit
Heat Exchanger Thermistor
Forecast of Cause :
1. Connector failure connection
Check Point 1 : Check connection of Connector
Check if connector is loose or removed
Check erroneous connection
Check if thermistor cable is open
>>Reset Power when reinstalling due to removed connector or incorrect wiring.
OK
Check Point 2 : Remove connector and check Thermistor resistance value
Thermistor Characteristics(Rough value)
Temperature (°C )
Resistance value (k )
Temperature (°C )
Resistance value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK
Check Point 3 : Check Voltage of Interface PCB (DC 5.0V)
Make sure circuit diagram of each hydraulic unit and check terminal voltage at Thermistor (DC5.0V)
BLACK
1 1
CN18
BLACK
2
2
If the voltage does not appear, replace Interface PCB and execute the check operation again.
Indicate or Display:
Hydraulic unit :
Green Red
4
n : n times blinking
Detective details:
Hydraulic unit thermistor is open or short is detected always.
2. Thermistor failure
-30 -25 -20
1131.9 804.5 579.6 422.9
20 25 30
62.9 49.7 39.6 31.7
H/E Thermistor
Outdoor unit : No indication
2
3. Interface PCB failure
-15 -10 -5
312.3 233.2 176.0
35 40 45 50
25.6 20.8 17.1
03-07
0 5 10 15
134.2 103.3 80.3
55 60 65
14.1 11.6 9.7
DC