It's an aluminum box with electronics inside it that is mounted above the glove box on W123s. One screw and one wiring harness. Look on fleabay for part number 0008221003 and you'll see a bunch of 'em for sale. Apparently it interacts with the pushbutton box, the sensors, the monovalve, etc.
Jim
--- In diesel_mercedes@yahoogroups.com, "Nate" <vwnate1@...> wrote:
>
>
> ?? wHAT IS THIS MYSTERY BOX ?? .
>
> -Nate
> Jim wrote:
> >
> > Solved heater problem 84 300D W123
> >
> > Symptoms:
> > - full heat all the time when temp dial anywhere but "MIN"
> > - full cold when in MIN detent
> >
> > Solution:
> > Part number 0008221003 - the mystery box
> >
> > - Junkyard pulls are all over ebay starting around $50.
> > - brinsonco.com has them for $115 reman by not-Programa/three year warranty
> >
> > Be aware that when other components upstream from this unit go bad, the problem can cascade downstream and burn out this box. These include the monovalve and the electric coolant boost pump. I checked my monovalve for resistance and it was 17, which was within the 11 to 19 acceptable range. I forget what the boost pump range is because I didn't check it...I put a new one on the car. ebay $90.
> >
> > Spending too much money on this car.
> >
> > Jim
> >
>
