i have mercedes e320cdi w210 and have problems with a heater. the heater wasnt working before i bought this car and it started to work today. the problem is that i cant turn it off. the only way to turn it off is disconnect a battery neg. terminal. if i try to do something on heater control panel it doesnt really do any changes even blower setting is set to 0(it still blows the air). so i got flattened battery very quickly. tried to remone fuse 4 and 7 under the hood.that didnt help either. how could i shut the blower off. any suggestions what could be wrong? thanks.