Reminds me of another GM vehicle with a jammed mode door, removed the top of the dash, and the cover, and found a piece of foam with self adhesive that fell of a piece of plastic mode door. Nothing wrong with the foam, not torn but caught between that door and the housing. How did they expect this to hold with 195* heat on it. First attempt was to glue it on with contact cement, that didn't last very long, second attempt, after gluing again, I cut a piece of 20 mil aluminum sized to fit inside of the frame with the door closed and riveted it. Sandwiching that foam, this lasted. May or may not be your problem, don't know until you look. 98 Ford Explorer had a like problem, but they used the wrong grade of plastic for that door, it warped. This was a mess, had to remove the evaporator box first that not only required removing it, but recovering the R-134a first. To get at this varies by vehicle, need an alldata.com subscription to learn what you have to do.