also check the lines going to your transfer case switch. there is a topic about this somewhere on the forums. if you have T case fluid in your lines theres a chance you could've gotten fluid up in the one of the vacuum reservoirs or whatever that control the vents. maybe even you heater core is going out? do a search you'll find something
2003 CC LS, indigo blue, Spectre Cold Air, OBX throttle body spacer, descreened MAF, hunter bull bar, BAJA off road lights, 15x7 Crager soft 8 wheels, 31x10.50x15 Goodyear Wrangler Authority tires, cranked TB's, Daystar 2 inch shackles, 2" PA body lift, 1.5 inch spacers in the rear, Access TonnoSport Tonneau cover, reese hitch, carbon fiber front chevy badge, Lund bug deflector, roof rack from a blazer, Kenwood CD player, JVC 6 1/2 speakers.