Fujitsu AUG12LVLB Service Instruction page 43

Trouble shooting 8
INDOOR UNIT Error Method:
Indoor heat ex. thermistor error
Detective Actuators:
Indoor unit Controller PCB
Heat exchanger (MID) thermistor
Forecast of Cause :
1. Connector failure connection 2. Thermistor failure 3. Controller PCB failure
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)
AB/ AU type
Temperature (°C)
Resistance Value (
Temperature (°C)
Resistance Value (
AR type
Temperature (°C)
Resistance Value (
Temperature (°C)
Resistance Value (
If Thermistor is either open or shorted, replace it and reset the power.
OK
Check Point 3 : Check voltage of Controller PCB (DC5.0V)
Make sure circuit diagram of each indoor unit and check terminal voltage at Thermistor (DC5.0V)
AU*G12/ 14/ 18LVLB
AR*G12/ 14/ 18LLTB
GRAY
1 1
CN5
GRAY
2 2
1
CN7
2
BLACK
1 1
CN8
BLACK
2 2
If the voltage does not appear, replace Controller PCB.
AMP Air Conditioning
Indicate or Display:
Refer to error code table.
Detective details:
Heat exchanger (MID) thermistor is open or short is detected always.
-30 -20
) 1131.9 579.6
25 30
49.7 39.6
)
-30 -20
) 1013.1 531.5
25 30
49.8 40.0
)
H/E (MID) Thermistor
Room Temp. Thermistor
-10 -5 0
312.3 233.2 176.0
35 40 45
31.7 25.6 20.8
-10 -5 0
292.9 221.1 168.6
35 40 45
32.4 26.3 21.6
AB*G18LVTB
BLACK
GRAY
1 1 1 1
CN5
BLACK
GRAY
2 2 2 2
1
CN7
2
Room Temp. Thermistor
BLACK
1 1
CN8
BLACK
2 2
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02-10
5 10 15
134.2 103.3 80.3
50 55 60
17.1 14.1 11.6
5 10 15
129.8 100.9 79.1
50 55 60
17.8 14.8 12.3
H/E (MID) Thermistor
20
62.9
63
10.4
20
62.5
63
11.1
DC