Daikin Cooling-Only Outdoor Unit RKN18AXVJU

EXV connector correctly connected to PCB

EXV generates a latching sound when power is turned off and on

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

Continuity confirmed when connector is disconnected and checked with a multimeter

Check the continuity between pins

For harness 5P models, check the continuity between pins

EXV coil is not faulty if there is continuity between the pins

If continuity is confirmed, proceed to next step

Outdoor PCB is not faulty if continuity is confirmed in previous step

In order to protect the environment, be sure to conduct pump down operation when relocating or disposing of the unit.

Valve caps removed from the liquid stop valve and the gas stop valve?

Forced cooling operation carried out?

Liquid stop valve closed with a hexagonal wrench?

Gas stop valve closed and forced cooling operation stopped?

Warning: This check requires trained personnel with PPE!

Measure the power supply waveform between No. 1(Live) and No. 2(Neutral) on the terminal board

Upload the oscilloscope reading

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

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

Sign off on the power supply waveforms check

Warning: Ensure the voltage between the terminal of Power transistor (+) and (-) is approx. 0 volt before proceeding

Voltage between the terminal of Power transistor (+) and (-) is approx. 0 volt

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

Measure resistance between power transistor (+) and (-) and the U terminal of the compressor connector

Measure resistance between power transistor (+) and (-) and the V terminal of the compressor connector

Measure resistance between power transistor (+) and (-) and the W terminal of the compressor connector

Evaluate the measurement results for a pass/fail judgment

Sign off on the power transistor check

Warning: Ensure the voltage between (+) and (-) of the diode bridge (DB1) is approximately 0 V before checking.

Enter the resistance between the pins of the DB1

Is the resistance ∞ or less than 1 kW?

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

Sign off on the main circuit short check