Daikin Indoor Unit Wall Mounted Type FTXJ20MV1BW

1. Check that the control voltage between the pins 10 - 11 is 15 VDC.

2. Check if the Hall IC generates the rotation pulse (0 ~ 15 VDC) 4 times between the pins 10 - 12, 10 - 13, when the fan motor i/s manually rotated once.

Make sure that the voltage of 320 ± 30 V is applied.

1. Set operation off and power off. Disconnect the connector S70.

2. Check that the voltage between the pins 4 - 7 is 320 VDC.

3. Check that the control voltage between the pins 3 - 4 is 15 VDC.

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: Ensure the voltage between (+) and (–) of the diode bridge (DB1) is approximately 0 V before checking.

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

Measure the resistance between the pins of the DB1.

Enter the resistance between the pins of the DB1

Is the resistance ∞ or less than 1 kΩ?

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

Sign off on the main circuit short check

Warning: Disconnect the connectors of the thermistors 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

Measure the resistance of the room temperature thermistor

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

Measure the resistance of the indoor heat exchanger thermistor

Sign off on the thermistor resistance 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?