Hi, I can answer your question, lets handle them one at a time. Click 'accept' when you are satisfied.. or we can get another expert.
Its the motor... however..those are the trickest of systems. They use 4 different micro computers to drive the unit, fan motor and compressor speed by means of varying the voltage and the frequency.. checking those systems out takes a factory trained Inverter AC tech, on site, and with the specialized and dedicated equipment to do a diagnosis.
It is not common for fan motor bearings to wear out so soon... but noise can only come from a mechanical source, and that would the fan motor in 99.9 percent of the cases.. that will not be an easy replacement job...and the electronics must be verified ok as well.
Let me know if you need further elaboration.
Thanks for the answer