Fujitsu AMUG24LMAS, Service Manual

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Thermistor characteristics (Rough value)
If thermistor is either open or shorted, replace it and reset the power.
Detective actuators:
Indoor unit controller PCB
Heat-exchanger (MID) 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
Troubleshooting 12
Indoor unit heat-exchanger middle
temperature sensor error
31.7 k Ω 39.6 k Ω 49.7 k Ω 62.9 k Ω 80.3 k Ω 103.3 k Ω
134.2 k Ω 176.0 k Ω
Resistance value
Temperature
Temperature
32°F (0°C) 41°F (5°C)
50°F (10°C)
1131.9 k Ω
-22°F (-30°C)
579.6 k Ω
-4°F (-20°C)
312.3 k Ω
14°F (-10°C)
233.2 k Ω
23°F (-5°C)
59°F (15°C) 68°F (20°C) 77°F (25°C) 86°F (30°C) 95°F (35°C)
17.1 k Ω 20.8 k Ω 25.6 k Ω Resistance value
Temperature
104°F (40°C) 113°F (45°C) 122°F (50°C)
14.1 k Ω
131°F (55°C)
11.6 k Ω
140°F (60°C)
10.4 k Ω
145.4°F (63°C)
Resistance value
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)
If the voltage does not appear, replace controller PCB.
Indicate or Display:
Indoor unit
Operation lamp: 4 times Flash,
Timer lamp : 2 times Flash
Wired remote control
Error code : [E : 42]
n: n times blinking : Light ON : Light OFF
Mode Error
2 5 15
Outdoor unit (AOUG36/48LMAS1)
03-17
H/E (mid.) temp.
thermistor
BLACK
BLACK
3
CN6
4
1 1
2 2
BLACK
BLACK
2
1
A B F E D C