i found an acc control in a 300sd and was hoping i could use it in a 300d. does anyone know if this can be done.

it cant be done.

The unit i found is from a 126. The part numbers are different and when you open them up the insides are way different.
The one i did have in the 300d was bad. Didnt control anything. I have the unit that i found in the car as it does seem in good working order. It only controls the fan and the temp. Strange thing is when I shut the car off the center vent open and when I start the car they close.

Sounds like the center vent switch is being controlled by one of the defrost vent or recirculate contacts. Maybe all you need is to review the appropriate wiring diagrams and move pins around to make it work.

Sixto
91 300SE
87 300SDL
83 300SD