Any way to REPAIR a blower motor regulator
 

Not sure yet if the problem I'm having with my blower not being able to blow out on the low setting, is caused by the blower motor regulator or not. I just replaced it 6 years ago. I mean, ....c'mon! These things should last longer than 6 years, especially at $250 a pop.

But if it IS the regulator, just wondering if there's any way to FIX the one I have, rather than replace. I guess it's a computer board in there that fails is what I heard.

1991 300d, 180k

The controller is a semiconductor and as such is not repairable. It's just barely possible that a substitution could be made but you'd have to reverse-engineer it after testing a good one. My own tests suggest a Darlington pair transistor might work but it actually could be an operational amplifier. What we need is an ex-Bosch (or whoever) employee willing to 'tell all.'

Try getting a used controller from a wrecking yard or used parts place, at least it will be less expensive. Note that there was a change when the cabin air filter was added (you don't give the year/model of your car).

Jeremy

1991 300d
 

Sorry about that; I added that in now to my original post.

The current regulator I have is only 6 years old, got it from Rusty, so it was a qualified OEM part from Germany. I can't believe 6 years is all you get from a $250 part. This is an outrage, not only because of the price, but the fact that it's so hard to get to, makes it even more painful.

I heard the circuit board gets fried after a while due to heat, but ...then they should make it better, to HANDLE the heat. Totally ridiculous that it lasts only this long.

circuits to regulate DC motors have been designed and deployed a million times. for example, PWM circuits are widely used. i think this is a solved problem.

however, i checked the schematic of my '77 and it only has a blower switch and two resistors (.8 ohm each). why did later cars get a transistorized regulator?

Schematics are over my head
 

But I think on mine, it's a circuit board. I simply can't believe they make them THIS BAD. My replacement one's only lasted 6 years.