Daikin Outdoor Unit Multi-Split Type Air Conditioner 3MXS24RMVJU

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 the power transistor test operation from the outdoor unit.

Forced cooling operation ON/OFF switch pressed for 5 seconds?

Diagnose according to 6 LEDs lighting status.

Warning: Check the main circuit for short circuit before proceeding

Warning: Never touch any live parts during the procedure

Voltage between FU2 and DC– is 50 V or less

Note: Ensure firm contact between the multimeter probes and the test points

Sign off on the capacitor voltage check

Warning: This procedure requires trained personnel with PPE!

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

Is the power supply waveform a sine wave as shown in Fig.1?

Is there any waveform disturbance near the zero-cross as shown in the sections circled in Fig.2?

Upload a photo of the measured waveform

Sign off on the power supply waveform check

Conduct the following to check the electronic expansion valve (EV).

1. Check if the EV connector is correctly inserted in the PCB. Match the EV unit number and the connector number.

2. Turn the power off and on again, and check if all the EVs generate a latching sound.

3. If any of the EVs does not generate a latching sound in the above step 2, disconnect that connector and check the continuity using a multimeter.

Check the continuity between the pins 5 - 1, 5 - 2, 5 - 3, 5 - 4. If there is no continuity between the pins, the EV coil is faulty.

4. If no EV generates a latching sound in the above step 2, the outdoor unit PCB is faulty.

5. If the continuity is confirmed in the above step 3, mount a good coil (which generated a latching sound) in the EV unit that did not generate a latching sound, and check if that EV generates a latching sound.

∗If a latching sound is generated, the outdoor unit PCB is faulty.

∗If a latching sound is not generated, the EV unit is faulty.

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

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

Resistance between the pins of the DB1

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

Short circuit on the main circuit?

Sign off on the main circuit short check