Fujitsu ASU18RMLQ Service Instruction page 55

Trouble shooting 22
OUTDOOR UNIT Error Method:
3-way valve Temperature
Thermistor Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
3-way valve Temperature Thermistor
Forecast of Cause :
1. Connector connection failure 2.Thermistor failure 3. Main PCB failure
Check Point 1 : Check connection of Connector
Check if connector is removed.
Check erroneous connection.
Check if thermistor cable is open.
>>Upon correcting the removed connector or mis-wiring, reset the power.
OK OK
Check Point 2 : Remove connector and check Thermistor resistance value Check Point 2 :
Thermistor Characteristics (Approx. value)
Temperature
Resistance Value (k )
Temperature
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK OK
Check Point 3 :
Check Point 3 : Check voltage of Main PCB (DC5.0V)
Make sure circuit diagram of outdoor unit and check terminal voltage at Thermistor (DC5.0V)
AOU24RML
BLACK
1 1 1
WHITE RED
3 2 2
WHITE
4 3 3
WHITE YELLOW
5 4 4
CN39
WHITE
6 5 5
WHITE BLUE
7 6 6
WHITE
8 7 7
WHITE BLACK
9 8 8
WHITE
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Refer to error code table.
Detective details:
When 3-way valve Temperature Thermistor open or short-circuit is
detected at power ON or while running the compressor.
14°F 23°F 32°F
(-10°C) (-5°C) (0°C)
312 233 176
104°F 122°F 140°F
(40°C)
(50°C) (60°C)
25.6 17.1 11.6
2-WAY VALVE A
3-WAY VALVE A
2-WAY VALVE B
3-WAY VALVE B
02-29
41°F 50°F 59°F 68°F
(5°C) (10°C) (15°C) (20°C)
134 103
80.3
158°F 176°F 194°F 212°F
(70°C) (80°C) (90°C) (100°C)
8.12 5.78 4.19
AOU36RML
VALVE THERMISTOR A, B
BLACK
1 1 1
WHITE RED
3 2 2
WHITE
4 3 3
WHITE YELLOW
5 4 4
CN39
WHITE
6 5 5
WHITE BLUE
7 6 6
WHITE
8 7 7
WHITE BLACK
9 8 8
WHITE
VALVE THERMISTOR C, D
BLACK
1 1 1
RED GRAY
2 2 2
RED
4 3 3
RED BROWN
5 4 4
CN40
RED
6 5 5
RED
ORANGE
6 6
7
RED
7 7
8
GREEN
RED
9 8 8
RED
86°F
(30°C)
62.9 39.6
3.09
2-WAY VALVE A
3-WAY VALVE A
2-WAY VALVE B
3-WAY VALVE B
2-WAY VALVE C
3-WAY VALVE C
2-WAY VALVE D
3-WAY VALVE D