mauried:
There are more than 2 possibilities.
Could be either 315 or 433 Mhz, but could also be AM or FM.
You need some kind of scanner to tell the differance.
Pufff.....I did not think, mauried
I don´t have a scanner and I don´t know anyone who has one..
raschemmel:
You mean a motorized Venetian blind for a window ?
Yep 
raschemmel:
Again I am going to ask you. by "engine" do you mean electric motor ? (that's what they're called in the USA. No one calls them "engines" in the US. Where are you from anyway ?
I think it is "electric motor", but "engine" also its a motor in English language (I´m spanish, raschemmel
)
raschemmel:
Without knowing the exact frequency of your remotes, there's no way to know what frequency the receivers are on inside the blind.
You may not be able to use those circuits unless you use the remote that came with them and use the arduino to close the contacts
on the remote. Remove the cover of the remote and take a photo of it showing the switch contacts and post the photo.
I have thought this but I expected that we could know with some cheaper method than buying a scanner.....
If I remove the cover, I break it (No screws, all with pressure..I've tried and it has been marked by the screwdriver..Very thin screwdriver)
jremington:
Again I am going to ask you. by "engine" do you mean electric motor ? (that's what they're called in the USA. No one calls them "engines" in the US. Where are you from anyway ?
What is your problem? It is completely obvious that that OP is referring to the motor + controller in the blind. That has nothing to do with the OP's question, which concerns radio frequency the remote controller uses.
Unfortunately, no responders in the forum have enough information to answer that question.
Yes, the question is about rf of the module inside the electric motor, and I put a thread because I have not found information about..
Thank you all for your answers, but like Mauried said, there are 4 possibilities...315, 433, AM and FM..
The only thing I can do is open the axis and remove the motor to see if there is any adhesive that tell me what I want to know or the brand of manufacturer.....
Thanks all 
Regards 