A faulty blower regulator. Using the VERY helpful and affordable services of www.justanswer.com , a 30 yr ASE technician, walked me through diagnosing the problem for $28!!! I happily tipped him as I installed the new regulator last night and everything is perfect. The part purchased through a Benz wholesaler was $146 shipped - as compared to the $450 Chrysler dealer quoted me, not to mention the $200 for labor. In all it took about 45 mins of actual diagnosis, removal, and installation. The toughest part was working upside down under the dash. Needless to say I will use this service EVERY time before going to a dealer. The guy I worked at justanswer.com is named Tim Mohr.