Smoke coming into the car

Hi I have a 94 cutlass oldsmobile cierra. I noticed a few times today, afew minutes after I would start the car, smoke would come inside through my vents. Then a few minutes later I didnt see it anymore, but the smell was still there ofcourse. What could it be? The is no smoke coming from under the hood. There isnt any smoke coming from the outside of the car at all. I didnt have the heat on either. In the past I have had a squeaky belt that has been fixed, and a new transmission. I have 242,000 miles on my car and I have a v6 engine. I also noticed when I looked under the hood that the side of the belt looks a little tore and it looks like it is sliding a little bit. Would that have anything to do with the smoke coming inside the car, or is that a totally diffefent problem by itself?