Fujitsu AMUG24LMAS Service Manual page 64

Troubleshooting 11
Room temperature sensor error
Detective actuators:
Indoor unit controller PCB circuit
Indoor temperature thermistor
Detective details:
Indoor unit thermistor is open or short
is detected always.
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)
Temperature
14°F (-10°C) 23°F (-5°C)
Resistance value
58.2 kΩ
Temperature 68°F (20°C) 77°F (25°C) 86°F (30°C) 95°F (35°C)
Resistance value
12.5 kΩ
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 indoor unit and check terminal voltage at thermistor (DC5.0V)
BLACK
1 1 1
CN5
BLACK
2 2
3
If the voltage does not appear, replace controller PCB.
44.0 kΩ
10.0 kΩ
Room temp.
thermistor
BLACK
BLACK
2
Indicate or Display:
Indoor unit
Operation lamp: 4 times Flash,
Timer lamp
Wired remote control
Error code : [E : 41]
Outdoor unit (AOUG36/48LMAS1)
Mode Error
2
: Light OFF
32°F (0°C) 41°F (5°C)
33.6 kΩ 25.9 kΩ
8.0 kΩ 6.5 kΩ
03-16
: 1 time Flash
A B C
15
5
: Light ON n : n times blinking
50°F (10°C) 59°F (15°C)
20.2 k 15.8 kΩ
104°F (40°C) 113°F (45°C)
5.3 kΩ 4.35 kΩ
D E F