Daikin Slim Duct Concealed Indoor Unit FDXS12DVJU

Warning: This procedure requires trained personnel with PPE!

Install the inverter checker 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 checker without touching each other?

Activate the power transistor test operation from the outdoor unit

Pressed the forced operation [ON/OFF] switch for 5 seconds?

Diagnose according to 6 LEDs lighting status

Conduct the followings to check the outdoor electronic expansion valve (EV).

1. Check to see 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 to see 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 tester.

Check the continuity between the pins 1 - 6 and 3 - 6, and between the pins 2 - 5 and 4 - 5. If there is no continuity between the pins, the EV coil is faulty.

4. If no EV generates 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 latching sound, and check to see if that EV generates latching sound.

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

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

Warning: This check 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

Warning: Ensure that the voltage between (+) and (–) of the power module (PM1) is approx. 0 V before proceeding

Voltage between (+) and (–) of the power module (PM1) is approx. 0 V

Disconnect the compressor harness connector from the outdoor unit PCB. To disengage the connector, press the protrusion on the connector.

Compressor harness connector successfully disconnected

Measure resistance between the terminals of the power module and the terminals of the compressor with a multi-tester.

Enter the resistance measurement

Evaluate the measurement results

Sign off on the power module check

With the power on, operation off, and the connector connected, check the following

Output voltage of about 5 V between pins 1 and 3

Generation of 3 pulses between pins 2 and 3 when the fan motor is operating