NOTE: I also posted in Tech-section '97 E300D: Which blower regulator to buy I have reviewed numerous posts on this subject and has been very helpful, but I still have questions. My blower only works in low and medium speeds. I don't think it's the pushbutton controller because the blower speed does not increase when defrost is selected. I went to this sites online catalog and it says I have to buy the blower with the regulator. Question #1) Is this true? Or can I just buy the regulator? Question #2) I was given a choice of two different regulators. Does anyone know the part number I need? Dr. Diesel had the following quote (different model Mercedes though) from a previous post to make sure the blower was OK: "... LEAVE THE KEY AND SYSTEM ON, DISCONNECT THE BLUE GND LEAD AT THE MOTOR FROM THE REG. CONNECT A JUMPER WIRE TO THE MOTOR TERMINAL AND GROUND THE MOTOR DIRECTLY TO CHASSIS. IF BLOWER RUNS FULL SPEED, REPLACE THE REGULATOR. ..." Question #3) can I run it like this as long as I would like or will bypassing the blower regulator damage the blower motor? IT'S VERY HOT DOWN HERE IN MOBILE, AL. Thanks guys. Can't wait till Mercedes finally gets some darn literature for my car. It's tough trying to figure this stuff out without a manual.

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Neil
1997 E300D - naturally aspirated
280,000 miles (as of November 2015)

Sadly, the original style regulator is no longer produced.
The new style (current production) is a retofit but requires replacing the blower motor as well to mount it and to keep it cool.
The job is an easy D.I.Y. but the parts are spendy.
If you can find an old reg sitting on a shelf somewhere, buy it.
When my 97 E420 reg. died, I looked through H**L and high-water to find one. I never found one, even at a wrecking yard.
I then broke down and bought the new parts.
Works good as new. Granted, $750 invested.
Sorry.
DR.D