2008 JKU X model... In winter, wife noted cold air coming in on her feet at highway speed. Pulled glove box to poke around and noticed the foam gasket between the upper air assembly, where air comes in from the cowl, and the lower hvac assembly, which includes the recirculate door, had deteriorated and disintegrated. So, even with recirculate button pressed, cold outside was able to blow in the cowl intake and blow down onto the passenger's feet. Fast forward to Texas summer, it's 105+ every day, and now hot air is invading at such a rate the a/c can't keep up. So, I needed to fill that gap where the foam gasket used to live. Very tight behind glove box, so removed speaker box. Used 1.25 inch foam backer rod, normally used to fill big gaps in caulking, and a very long forceps style pliers to work it in, I could just get a free hand around the left and right sides to make sure the backer rod was properly wedged into the gap in the back along the firewall and both sides, and then the front. Replaced speaker box and glove box. Voila! No more infiltrating outside air! A/c keeping us nice and cool. So, why a foam gasket, about an inch thick, that will predictably disintegrate? Is it to allow a bit of outside air to always mix into the cabin? PITA to repair. Imho, bad design.
