I have a 2000, we went on a long trip, i let my wife drive, and DAMN the passenger side doe have a air leak. It was on recirculate to. I talked with my brother-in-law that has the same year burb, he has the same problem.
I think it comes in "around" where the blower motor seals, I have yet to pull it apart. I think I will just drive from now and on!