Blower Motors (HVAC)
 

The problem is:
1.Bosch did not use Bearings,they used Bushings.
(If they had used 2RS [2 Rubber Sealed] Type Bearings with Synthetic High Temp Lube...You'd NEVER have a Bearing Problem.)
[Bosch does the same "Trick" in their Starters,Bushings instead of bearings,
ONLY the Bushings used in the Starters are much more Stout.]
Bushings. Bearings. Whatever!
Let the slightest "Slop" develop and the Rotors,Brushes and Contact Points
self destruct at a needlessly Early stage.
2.Brushes Wear,and when they've worn enough,Resistance Increases.
[If your Already Worn, Needlessly High Resistance Brushes are ALSO fighting
a ROTATIONAL FRICTION from BUSHINGS,you get even more Resistance.]
3.The Bean Counter,Exkrementkopf/Scheißer (s) in Stuttgart gifted your Mercedes with BARELY Adequate wiring in the HVAC circuit.

So,If you're LUCKY your Blower will Implode.
Mayhaps taking the Controller with it.

If you're unfortunate...
The Controller will, with Teutonic Determination,Power
the Blower until the Resistance results in the NOW Outright Dangerously
UNDERSIZED WIRING Catching Fire.
AND Car-B-Que ing your Mercedes around your ears.

Mercedes Engineers WOULD NEVER allow such Stupidity.