Daikin Cassette Type Indoor Unit FDBT42NUV2S

Warning: Do not touch the energized part (high voltage part) for at least 10 minutes after the power is turned OFF.

Be sure to touch the earth terminal with a hand to release static electricity from the body (to prevent PCB from being damaged).

Confirm that residual electric charge of the power transistor is DC 50V or less.

After checking the residual electric charge, remove the connector of the outdoor unit fan motor.

Confirm that the outdoor unit fan has stopped.

Remove the wire connecting the power transistor and the compressor. Remove it from the compressor terminal side.

During this work, be careful not to deform. Faston terminal at the end of the relay wire.

Measure resistance and fill in the blanks in the following table.

Check if there is unbalanced resistance for one of the 3 phases in each table (when the resistance value is equal to 5 times or more than the other resistance values), the power transistor is broken.

Check for Fan Motor Connector (Signal Line)

(2) With the fan motor connector disconnected, measure the resistance between each pin, then make sure that the resistance is more than the value mentioned in the following table.

(2) With the fan motor connector disconnected, measure the resistance between each pin, then make sure that the resistance is balanced in ±30%.

Check for Fan Motor Connector (Power Supply Line)

With the relay connector disconnected, measure the resistance between UVW phases of the connector (3 cores) at the motor side, then make sure that the resistance between each phase is balanced and not short-circuited.;

Temperature differences must occur before or after the clogged points!

Replace the electronic expansion valve.

Blow a nitrogen gas, and then replace the refrigerant.

Replace the heat exchanger or distributor.

Collapsed pipe Replace the pipe.

Warning: Disconnect the thermistor from the PCB before proceeding

Thermistor disconnected from the PCB

Upload a photo of the table with the measured values

Do the measured values correspond with the values in the table?

Sign off on the thermistor check

Set operation OFF and power OFF. Disconnect the connector.

Keep operation OFF and power OFF. Connect the connector.

2 pulses (0 and 5 VDC) are output 4 times at the pins 1 - 4 when the fan motor is rotated 1 turn by hand.

Sign off on the fan motor pulse check