Daikin Indoor Unit Multi-Split Type Air Conditioner FVXS12NVJU

Warning: Disconnect the connectors of the thermistors from the PCB before proceeding

Thermistors disconnected 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 to measure the resistance

Room temperature thermistor removed from the 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 and measure the resistance

Indoor heat exchanger thermistor removed from the PCB

Measure the resistance of the indoor heat exchanger thermistor

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: This procedure requires trained personnel with PPE!

EV connector correctly inserted in the PCB

All EVs generate a latching sound after power cycle

If any EV does not generate a latching sound, proceed to next step

If there is no continuity between the pins, the EV coil is faulty

Make sure that the voltage of 320 V is applied.

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

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

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

Check that the rotation command voltage between the pins 4 - 2 is 0 ~ 15 VDC.

Keep operation off and power off. Connect the connector S70.

Check whether 4 pulses (0 ~ 15 VDC) are input at the pins 4 - 1 when the outdoor fan motor is rotated 1 turn by hand.

When the fuse is melted, check the outdoor fan motor for proper function.

Warning: This check requires trained personnel with PPE!

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

Upload a photo of the measured waveform

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

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

Sign off on the power supply waveform check