Daikin Ceiling Concealed Duct Type Heat Pump Indoor Unit FLXS35BAVMB

EV connector correctly connected to the PCB

EV generates a latching sound when power is turned off and on again

Continuity confirmed when connector is disconnected and checked with a multimeter

Check the continuity between the pins

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

If the continuity is confirmed, the outdoor unit PCB is faulty

Sign off on the electronic expansion valve check

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

Thermistors disconnected from the PCB

Measure the resistance of the room temperature thermistor using 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

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

If OK in both steps (1) and (2)

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?

Diagnose according to 6 LEDs lighting status

If all the LEDs are lit uniformly, the compressor is defective. Replace the compressor.

Warning: This check requires trained personnel with PPE!

Is the power supply waveform between No. 1 and No. 2 on the terminal board a sine wave?

Is there waveform disturbance near the zero-cross?

Upload a photo of the waveform disturbance near the zero-cross

Sign off on the power supply waveforms check