Ok lets address the warranty issue first. Your vehicle should be under a gm warranty depending on the actual delivery date. If you post the last 8 digits of your vin# XXXXX can verify this for you.
As far as the actual problem is concerned, do you hear the a/c compressor operating when you select a/c? When you change the temp setting, does everything seems as it should, but you just simply have no blower motor activation?