heater blower wont switch off

[big kerr]

i have an 02 plate e320 cdi old shape ,the heater motor/blower is on full power and wont switch off ,even with ignition key out,any ideas !!!

 

[Diesel Benz]

Heater blower regulator blown (to short circuit). I had the same on my 210.026 (or do you mean W211 pre-face lift?), when it was pretty new. Take care of your battery, it would run out soon when the blower is running but the car is not.

 

[grober]

If its like the older models the heater motor is always "hot" i.e. has a direct live feed. The speed is altered by changing the voltage at the negative side of the motor which varies the voltage across the motor windings and alters the speed. this used to be done with an array of resistors but now its done by solid state switching I think? As DIESEL BENZ says its probably the regulator thats gone. Could be further back at the heater/aircon control level but less likely. Replacing the regulator should cure your problem---DONT LET THE BATTERY GO FLAT! quite a few posts about this on the forum.