Hey all the heater in my 2000 300M just recently got stuck at max heat and in defrost mode. The digtal display lights show the mode changing but it only blows hot air on the windshield. The display lights also show the temp changing up/down when I adjust it but the temp stays and full heat . The fans speeds works fine and the A/C is not on while the defrost is blowing the heat if that makes any difference. My 103 mile drive to work every morning with freezing feet/hot face is getting old quick ! Any ideas where to start looking? Thanks for your help