W210 blower fan
 

quit working so we replaced the regulator/ now fan just comes on and off at random, heater/ac works great. New part was the w210-9094302385 that is a replacement for the original. What could be causing the random fan, mostly runs about 10 - 30 seconds and then off. :confused:

Don't you have to replace the blower motor to use the newer regulator? I know that when my regulator stopped working on my 1997 E420 (would only blow at low speed), I wound up getting a used blower with regulator to avoid having to spend over $800 on new parts. Did the regulator match the one you took out?

this is the 2nd time we have replaced the regulator, 1st time we used the W410 and redid the wiring, soldering as directed and this produced a satisfactory result for nearly 2 years. We tried that again and it did not work, bought a W210 regulator that was suppose to be an original parts replacement. The part that bolts to the fan motor is smaller than the original but otherwise bolts up fine and wiring correct. What other part could be causing the random off/on situation

worn brushes in the motor??