Fujitsu ASU18RLF Service Instructions Manual page 52

Trouble shooting 8
INDOOR UNIT Error Method:
Indoor Room Thermistor Error
Detective Actuators:
Indoor unit controller PCB circuit
Room temperature thermistor
Forecast of Cause:
1. Connector failure connection 2. Thermistor failure
Test 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
Test 2 : Remove connector and check Thermistor resistance value
Thermistor Characteristics (Rough value)
Temperature (°C)
Temperature (°F)
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK
Test 3 : Check voltage of Controller PCB (DC5.0V)
Make sure circuit diagram of each indoor unit and check terminal voltage at Thermistor (DC5.0V)
Compact wall mount circuit diagram(Connector connection)
BLACK
1 1
H/E Thermistor
BLACK
2 2
CN4
BLACK
3 3
Room Temp. Thermistor
BLACK
4 4
Wall mount circuit diagram (Direct soldering to PCB)
H/E Thermistor
RED
BLACK
1 1
1
CN3
2 2
2 WHITE
BLACK
3 3
BLACK
1
Room Temp. Thermistor
CN1
BLACK
2
Floor circuit diagram (Connector connection and Direct soldering to PCB)
GRAY
1 1
H/E (MID) Thermistor
CN3
GRAY
2 2
BLACK
1
Room Temp. Thermistor
CN1
BLACK
2
If the voltage does not appear, replace Controller PCB and execute the check operation again.
Indicate of Display:
Indoor Unit
Operation lamp : 4 time Flash
Timer lamp
ERROR CODE : [E : 41]
Detective details:
Room temperature thermistor is open or short is detected always.
3. Controller PCB failure
-10 0
10 20
14 32
50 68
58.25 33.62 20.17 12.54
Compact cassette circuit diagram (Connector connection)
1
CN5
2
1 1
CN8
2 2
Slim duct circuit diagram (Connector connection)
1
CN5
2
1
CN7
2
1 1
CN8
2 2
02-12
Outdoor Unit
A
: 1 time Flash
: Light ON
30 40 45
86 104 113
8.04 5.30 4.35
GRAY
1
H/E (MID) Thermistor
GRAY
2
BLACK
Room Temp. Thermistor
BLACK
GRAY
1
H/E (MID) Thermistor
GRAY
2
BLACK
Room Temp. Thermistor
BLACK
Monitor
B C D E F
: Light OFF n : n time blinking