Fujitsu ASU7RLF1 Service Instructions Manual page 55

Trouble shooting 18-2
OUTDOOR UNIT Error Method:
Heat Ex. MID Thermistor Error
Detective Actuators:
Outdoor Unit Main PCB Circuit
Heat Exchanger 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
Check Point 2 : Remove connector and check Thermistor resistance value
Thermistor Characteristics (Approx. value)
Temperature(°F)
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
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
GREEN 2
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 : 73]
Detective details:
When Heat Exchanger Temperature Thermistor open or short-circuit is
detected at power ON or while running the compressor.
14°F 23°F 32°F
27.8 21.0 16.1
THERMISTOR
(PIPE MID)
THERMISTOR
(HEAT SINK)
THERMISTOR
(COMPRESSOR)
THERMISTOR
(OUTDOOR)
THERMISTOR
(PIPE)
THERMISTOR
(DISCHARGE)
LED 1 : 16 time Flash
: Operation lamp: 7 time Flash, Timer lamp: 3 time Flash
Economy lamp: Continuous flash.
41°F 50°F 59°F 68°C
12.4 9.63 7.56 5.98
02-23
77°F
86°F
4.77 3.84