I have more information about the problem:

When I ignite the engine and I turn on the A/C I put the maximum power of the flow (I touch the button for the flow speed to the maximum). The A/C works fine, with the maximum speed of the flow... but after 5 or 10 minutes, the speed of the air flow decreases, I don't touch any button, I don't touch nothing .

The A/C decreases the speed automatically after a few minutes but I don't know the reason. After it, I can't increase the speed of the flow to the maximum power. The display of the flow power marks the maximum power, but It isn't true, because it decreases, but the display marks the maximum power... why????

Thank you in advance.
Regards