Loud noise from the climate control

[lmottel]

I just bought a 2007 G35S sedan. While I was driving it on the road I noticed a steady noise coming out from the AC. It is not the "normal" AC noise, kind of like a high pitched grinding noise. I took it to the dealer and they checked it out and said they cant find anything, and it is normal for the G35S...As soon as I turn off the AC the sound is gone. They turned on a G35 for me and it did not have the noise as my G35S has...but again, they said it is normal for the S...anyone else having the same or similar issue?

thanks