[Attention, do not try this w/o a electronics technician that can give you warranties that your air conditioner will not be damaged! You have been warned!]
A few months later...
I talked to a friend that understand electronics.
He said that removing the buzzer completely could not cause any problems.
But before trying that drastic solution, first I tried just to remove the buzzer cover to try to put something inside the buzzer to lower the noise.
But then... to my surprise, the buzzer came out completely and cleanly w/o damaging the circuit board (probably it was weakly soldered), by luck I guess...
I've been using the air conditioner w/o noises since then.
So... for that model it is not causing any trouble that I can detect to the date.
This doesn't mean there is no problem there!!!
I am just sharing what happened and is apparently working w/o problems, but I do not understand electronics myself so I cannot explain if it is or is not causing problems!!!
Also, the buzzer is used to provide diagnostic data thru a cell phone call by making noises like a fax I guess, so that functionality became unavailable until I plug the buzzer back again.
If you want to try this, talk to some friend that understand electronics first, and better ask him to manipulate the buzzer so that you wont damage it, and if possible ask him to test if the circuit could be failing somehow so he can solder it (or something else less irritating, may be a led?) back if something looks wrong.
I risked myself damaging the air conditioner... totally out of real despair, because of the absurdly irritating noise, I should never have bought that model initially at all!!! (and will never buy again w/o being sure it is possible to disable the noises w/o risking damaging it).
I do not recommend doing it w/o someone that understand the electronics of the model of your specific air conditioner, ask a technician to help you tweak the hardware, and to give you warranty in case some problem happens, that would be the most safe way for sure.
If you think I could share this text in a way ppl will understand the risks better, say so or edit it please. I am just sharing that it is working but I cannot guarantee there is no problems...
If you understand electronics, you could explain us why it is apparently not causing any troubles? or even better, what problems may happen if I keep it w/o the buzzer?