Ok, it has became evident that the 97-99 Jeeps were prone to the plastic piece that inserts into the defroster door breaking. So, there is a metal bar that comes out of the air plunger that opens and closes the defroster door. Unattach the metal bar from the plastic piece that inserts in to the defroster door. If it is broken, like mine was, there was a small hole in the bottom of it. The piece that breaks off "inside" of the defroster door has a small hole in it also. I went to the local hardware store, I bought a #8 x 2" phillips pan head sheet metal screw, and a #8 flat washer. All together .50 cents!! I stuck the plastic piece back into the defroster door and then inserted the sheet metal screw and threaded until it was tight. Started the Jeep, turned on the defrost and the door opened perfectly. I was going to take complete pictures, but, the batteries went dead in the camera. I will post a completed picture later tonight when I get home. Some folks said to fix it you will have to take the entire dash apart, I didn't and it took me less than 10 minutes tops.