Took the Grand Prix out of winter storage this past week & so far so good, but I did run into a little hiccup with the climate control system. I have the basic single zone 3-knob setup. What happened is its stuck on the bi-level setting (blowing from dash & floor) which is where it was when I put it away for the winter. There is no vacuum tension trying to change modes. It just turns without feeling much if any resistance, but doesn't feel like the plastic knob itself broken (went through a lot of those years ago with my old grand am). I also thought it would default to defrost mode if there was a vacuum problem. Is there anything common that would cause this to happen before I start tearing everything apart?
