Fujitsu ASU7RLF1 Service Instructions Manual page 53

Trouble shooting 17
OUTDOOR UNIT Error Method:
Compressor Thermistor Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Compressor 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 miss-wiring, reset the power.
OK OK
Check Point 2 : Remove connector and check Thermistor resistance value
Thermistor Characteristics (Rough value)
Temperature(°F)
Resistance Value (k )
Temperature(°F)
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK OK
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)
1
CN24
BLACK
2
WHITE
1
CN25
BLACK
2
BLACK
1
CN26
BROWN
2
GREEN
1
CN23
BLUE
BLUE
2
1
CN22
BLACK
2
RED
1
CN21
BROWN
YELLOW 2
If the voltage does not appear, replace Main PCB.
Indicate or Display:
Outdoor Unit :
Indoor Unit
ERROR CODE : [E : 72]
Detective details:
When Compressor Temperature Thermistor open or short-circuit is
detected at power ON or while running the compressor.
32°F 41°F 50°F
169 130 101
158°F 176°F 194°F
8.69 6.27 4.60
THERMISTOR
(PIPE MID)
THERMISTOR
(HEAT SINK)
THERMISTOR
(COMPRESSOR)
THERMISTOR
(OUTDOOR)
THERMISTOR
(PIPE)
THERMISTOR
(DISCHARGE)
LED 1 : 7 time Flash
: Operation lamp: 7 time Flash, Timer lamp: 2 time Flash
Economy lamp: Continuous flash.
59°F 68°F 86°F 104°F
79.1 62.5 40.0 26.3
212°F 248°F
3.43 2.00
02-21
122°F 140°F
12.3
17.8