Daikin Indoor Unit Wall Mounted Type Air Conditioner FTX25KV1B

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).

Fan motor wire breakdown / short circuit check

1. Check the connector for connection.

3. Check if each resistance at the phases U - V and V - W is 90 Ω ~ 100 Ω (between the pins; 12 - 9, and between 9 - 6).

1. Check the connector for connection.

2. Check the motor control voltage is generated (between the pins 2 - 3).

1. Check the connector for connection.

Warning: This check requires trained personnel with PPE!

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

Is the power supply waveform a sine wave?

Is there waveform disturbance near the zero-cross?

Sign off on the power supply waveforms check

Warning: This procedure requires trained personnel with PPE!

Turn off the power before starting the procedure.

Install an inverter analyzer instead of a compressor.

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

Enter the voltage of the built-in smoothing electrolytic capacitor

Connect the terminals to the terminals of the inverter analyzer.

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

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, a short circuit occurs on the main circuit

Sign off on the main circuit short check