Daikin Indoor Unit Wall Mounted Type FTXJ50LV1BW

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: This procedure requires trained personnel with PPE!

Install an inverter analyzer instead of a compressor

Charged voltage of the built-in smoothing electrolytic capacitor dropped to 10 VDC or below?

Terminals removed from the compressor?

Terminals connected to the terminals of the inverter analyzer without touching each other?

Activate power transistor test operation from the indoor unit

FAN operation selected with the Mode button on the remote controller?

Warning: This check requires trained personnel with PPE!

Voltage between (+) and (-) of the diode bridge (DB1)

If voltage is not approximately 0V, report the issue and stop the procedure

Resistance between the pins of the DB1

If the resistance is ∞ or less than 1 kΩ, short circuit occurs on the main circuit.

Sign off on the main circuit short 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: Disconnect the connectors of the thermistors from the PCB before proceeding

Thermistors disconnected from the PCB

Measure the resistance of each thermistor using a multimeter

If the room temperature thermistor is soldered on a PCB, remove the PCB from the control PCB

PCB removed from the control PCB

Measure the resistance of the room temperature thermistor

If the connector of indoor heat exchanger thermistor is soldered on a PCB, remove the thermistor

Indoor heat exchanger thermistor removed

Measure the resistance of the indoor heat exchanger thermistor