Hi Folks.
New here. Rob from Australia.
I have a 2011 W204 C250 CDI. It drains battery power overnight sometimes.
I caught the blower motor running an hour after I switched the car off.
It is obviously related to the regulator as one side is permanent power all the time.
I removed the regulator which is the flat type not the Porcupine type.
It runs off fuse no 12. What I am wondering is if anyone has put a relay on the power feed and then switched it with an accessory trigger wire?
Or does it already have a relay in the fuse box? That way I can change the input for it to an accessory feed there.
I am doing this so the same thing doesn't happen again. I am replacing the regulator as well.
Thanks. Rob.

 

OK.
I did the mod.
Just put a relay in-line and got accessory power from fuse box.
All fixed.