Hmmm...I am experiencing the same problem on my 1997 S500 coupe. I replaced the blower regulator and everything worked fine for about two weeks. Now, I am having uncontrolled fan surges and no shut off after I turn the car off. I also replaced two of the relays that are supposed to control the blower.

Trying to figure out my next move. I need a scan tool, but I am unsure of which one will be the most useful at a reasonable price. Any help?