E: 42.↓. Indoor Unit Heat Exchanger Sensor Error (Indoor Unit) - Fujitsu ASUH18LMAS Service Manual

2-12. E: 42.X. Indoor unit heat exchanger sensor error (Indoor
unit)
Indoor unit
Indicator
outdoor unit
Indoor unit main PCB
Detective actuator
Heat exchanger 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 heat exchanger thermistor resistance value, refer to
tance values" on page 03-88.
• 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 each indoor unit and check terminal voltage at thermis-
tor (DC 5.0 V).
NOTE: For details of thermistor connector, refer to
TECHNICAL DATA AND PARTS LIST on page 02-18.
If the voltage does not appear, replace main PCB.
2-12. E: 42.↓. Indoor unit heat exchanger sensor error (Indoor unit)
Operation indicator
Timer indicator
Economy indicator
Error code
Refer to
→hen heat exchanger temperature thermistor open or
short circuit is detected.
"→iring diagrams"
End
- (03-27) -
4 time flash
2 time flash
Continuous flash
E: 42
"Error code table (Outdoor unit)"
Connector connection failure
Thermistor failure
Main PCB failure
"Thermistor resis-
in Chapter 2.
on page 03-4
2. Troubleshooting with error code