Air vent problem on my c230
 

My air only blows through the vent and the Defrost, if i change it to the floor nothing happens.. Always through the Vent and the Defrost..My local shop told me the Heater Case, behind the glovebox, is bad. The part from MB is $950 bucks. Does anyone have any thoughts, I would like to know that if i spend that kind of cash it will fix the problem.. I dont want to through $950 into it and have the same symptoms.

Thanks

OH and one more thing,,, my radiator fan starts right after I start the car and stays on, cold or not, until I turn the car off