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2-14. E: 74. Outdoor temperature thermistor error (Outdoor unit)

Indicator Indoor unit

Operation indicator 7 time flash

Timer indicator 4 time flash

Economy indicator Continuous flash

Error code E: 74

Detective actuator

Outdoor unit main PCB When outdoor temperature thermistor open or short

circuit is detected at power on or while running the

compressor

Outdoor temperature thermistor

Forecast of cause

Connector failure

Thermistor failure

Main PCB failure

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 "Thermistor re-

sistance values" on page 03-43.

• 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 "Wiring diagrams" in Chapter 2.

TECHNICAL DATA AND PARTS LIST.

If the voltage does not appear, replace main PCB.

↓

End

2-14. E: 74. Outdoor temperature thermistor error (Outdoor unit) - (03-18) - 2. Troubleshooting with error code

TROUBLESHOOTING

Fujitsu AOYG09KHCAN User Manual

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