Mercedes Blower Motor Resistor
 

Hello, can anybody help me with a certain car part?

The Blow Motor Resistor malfunctioned on my uncles car, and he can not find an schematic anywhere on how to test it, or even recreate it (he is an electrician). It is an benz A214/C214 124 820 27 10 part.

Any info would be very appreciated.

That part is actually called the blower motor regulator. It can be rather difficult to test as I've read. I think either its a form of PWM based control or some kind of current regulator. I haven't really looked at the much into it. Basically its fed a 0-7V signal where (I think) 7 = full fan speed, and 0V= no fan speed.

This guy made his own control circuit:
http://www.benzworld.org/forums/w210-e-class/1516551-blower-motor-regulator-fix-make-your.html

they just go... easy fix