Daikin Indoor Unit Wall Mounted Type FTXJ20LV1BS

EV connector correctly connected to the PCB

EV generates a latching sound when power is turned off and on again

Continuity confirmed when connector is disconnected and checked with a multimeter

Check the continuity between the pins

Sign off on the electronic expansion valve check

Measure the power supply waveform between No. 1 and No. 2 on the terminal board

Check if the power supply waveform is a sine wave (Fig.1)

Check if there is waveform disturbance near the zero-cross (sections circled in Fig.2)

Sign off on the power supply waveforms check

Warning: This procedure requires trained personnel with PPE!

If power is not turned off, stop the procedure and turn off the power

Install an inverter analyzer instead of a compressor

Ensure the charged voltage of the built-in smoothing electrolytic capacitor drops to 10 VDC or below before carrying out the service work

Remove the terminals from the compressor

Connect the terminals to the terminals of the inverter analyzer

Warning: Be careful not to let the terminals (U,V,W) touch each other. Otherwise, high voltage is applied

Activate power transistor test operation from the indoor unit

Check the connection of connector

Check the motor power supply voltage output (pins 4 - 7)

Check the motor control voltage (pins 4 - 3)

Check the rotation command voltage (pins 4 - 2)

Check the rotation pulse (pins 4 - 1)

Sign off on the fan motor connector output check

Warning: Ensure the voltage between (+) and (-) of the power module is approximately 0 V before proceeding.

Voltage between (+) and (-) of the power module is approximately 0 V?

Disconnect the compressor harness connector from the outdoor unit PCB. To disengage the connector, press the protrusion on the connector.

Compressor harness connector disconnected from the outdoor unit PCB?

Measure resistance between the (+) or (-) terminal of the power module and the U, V, or W terminal of the compressor with a multimeter.

Enter the resistance measurement

Evaluate the measurement results

Sign off on the power module check