Daikin Indoor Unit Wall Mounted Type Air Conditioner FTX20K2V1B

Warning: Ensure the voltage between (+) and (–) of the diode bridge (DB1) is about 0 V before proceeding

Enter the voltage between (+) and (–) of the diode bridge (DB1)

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

Enter the resistance between the pins of the DB1

Compare the resistance with the table

Does the resistance indicate a short circuit?

Sign off on the main circuit short check

Warning: This check requires trained personnel with PPE!

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)

Upload a photo of the measured waveform

Sign off on the power supply waveforms check

Ensure that the voltage of 320 + 100 V ~ 320 - 50 V is applied

Set operation off and power off. Disconnect the connector S70 or S71

Control voltage between the pins 3 - 4

Rotation command voltage between the pins 2 - 4

Keep operation off and power off. Connect the connector S70 or S71

4 rotation pulses (0 ~ 15 VDC) at the pins 1 - 4 when the fan motor is rotated 1 turn by hand

If NG in step 2 → Defective PCB → Replace the outdoor unit PCB (main PCB)

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 to measure the resistance

Room temperature thermistor removed from the 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 and measure the resistance

Indoor heat exchanger thermistor removed from the PCB?

Measure the resistance of the indoor heat exchanger thermistor

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?

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

Power transistor test operation activated from the indoor unit?

Diagnose method (Diagnose according to 6 LEDs lighting status.)