Daikin Outdoor Unit Standard Multi-Split Type Air Conditioner 5MXS48WVJU9

Warning: This procedure requires trained personnel with PPE!

Set operation OFF and power OFF. Disconnect the connector S70.

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.

Pulses at the pins 1 - 4 when the fan motor is rotated 1 turn by hand

Warning: This procedure requires trained personnel with PPE!

Disconnect the connector of thermistor ASSY from the PCB to measure the resistance between the pins using multimeter.

Enter the measured resistance value

Does the measured resistance value match the listed value?

To check the thermistor soldered on a PCB, disconnect the PCB from other PCB/parts, and measure the resistance between the both ends of soldered thermistor.

Enter the measured resistance value

Does the measured resistance value match the listed value?

Note: When replacing the defective thermistor(s), replace the thermistor as ASSY;

Sign off on the thermistor resistance check

Warning: This check requires trained personnel with PPE!

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

Is the power supply waveform a sine wave (Fig.1)?

Is there waveform disturbance near the zero-cross (sections circled in Fig.2)?

Upload a photo of the measured waveform

Sign off on the power supply waveform check

Conduct the followings 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 latching sound.

3. If any of the EVs does not generate 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 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.

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