E: 74. Outdoor Temperature Thermistor Error (Outdoor Unit) - Fujitsu ACUH09LUAS1 Service Manual

2-23. E: 74. Outdoor temperature thermistor error (Outdoor unit)

→ired remote
Indicator
controller
Outdoor unit main PCB
Detective actuator
Outdoor temperature thermistor
Forecast of cause
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.
Check point 2. Remove connector and check thermistor resistance value
• For the outdoor temperature thermistor resistance value, refer to
sistance values"
• If thermistor is either open or shorted, replace it and reset the power.
Check point 3. Check voltage of main PCB
Make sure circuit diagram of outdoor unit and check terminal voltage at thermistor
(DC 5.0 V).
NOTE: For details of thermistor connector, refer to
TECHNICAL DATA AND PARTS LIST on page 02-22.
If the voltage does not appear, replace main PCB.
2-23. E: 74. Outdoor temperature thermistor error (Outdoor unit)
Error code
on page 03-53.
End
→hen outdoor temperature thermistor open or short
circuit is detected at power on or while running the
compressor
Connector failure
Thermistor failure
Main PCB failure
"Thermistor re-
"→iring diagrams"
- (03-28) -
E: 74
in Chapter 2.
2. Troubleshooting with error code