w210 heater problem e320cdi

[eima007]

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.
any suggestions what could be wrong? thanks

 

[24 VRT]

You will probably get a better response by posting this in the Electronics section - sounds like a blower fan problem rather than no hot coolant circulating from the engine.