W210 fan speed won't change?
 

My sis-in-law has a 1997 W210 E420. Recently, the cabin fan began acting up. The A/C blows cold air, however, the fan only blows at the lowest speed. In auto mode, the display indicates that the fan should go higher, but it doesn't. In manual mode, same thing, the fan stays at the lowest speed.

Any ideas?

Thanks!

Bad regulator, probably.

I'm not sure when the change was made, but the regulator and blower motor were updated. If you have the earlier type (I think it's likely), you are supposed to change both of them if either fails.

However, I do recall reading about a way to modify a certain 140 blower motor regulator to work with the old-style 210 blower. Try searching for such things.

Thanks Matt. I'll do some searching...

I would stay away from the mod, and go with the new blower motor and regulator fix.

I'd prefer to do that, but then you're talking about a whole bunch of money.

The modified W140 regulator seems like a good option, why would it not be a good idea?

Only because it's not an MB approved fit. But not everything I do is MB approved.

I see. FWIW, the repair shop that my sis-in-law contacted recommended against the W140 regulator. Instead, they believe they can source an old-style W210 regulator. I'll follow-up with more later...

Why would you want the old style regulator.. they would not take the current demands.. which is why guys replace them with the 140 unit conversion..

http://www.peachparts.com/Wikka/W140BlowerMotor

I had the same problem awhile back,same car same year.The regulator is under the glowebox and it cost 250 canadian dollars at the time.It did it for me.

Thanks Arthur. If it were me, I'd go with the 140 unit. I'll pass along this info.