Air Conditioning Problem

[07typeS]

Has anyone had a problem with their air conditioning at all? The other day I went to my car after getting off work and because the morning weas cool, it was on the defroster mode when i turned the car on. When I tried to switch it from defroster to normal vents it didnt sound like it switched over but i had assumed it did. Later on in the day i got back in the car, noticed a little different noise and went to turn the airconditioning up and all of a sudden i got this almost high rpm motor noise, like the shaft was spinning super fast because it lost its fan blade or a pump thats suppose to be submerged in fluid but you pull it out into air.... thats the difference in sound.

Has anyone experienced anything like that?

I am going to take it into the dealership but am curious how they are going to look at it with the aftermarket stereo installed... any tips with the stereo before i take it in?