The sensor in the front of the car is for outside air temperature it shouldn't stop the blower motor from working.I am not very knowledgeable in Mercedes but if you need test procedures wiring diagrams ect...... There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online