OK!
This is stuff all of u 123 guys i know have had problems with!
My center vents are not closing and opening. I pulled apart the glove box and lower dash to watch the little vaccum thing (i don't know what its called) move the lever, and it had enough strength to close it but not open it. I would help the little lever along and once it turned to a certain degree, it would open the vents, but it can't do it on its own. i checked the vaccum tube and it seems ok.
Id like to replace this part of buy the kit to repair it because i want those center vents to work!
Has anyone done this? Its very far back in the dashboard and hard to reach. This is for a 1983 300D.
Thanks all!

Get a Mighty Mite hand held vacuum pump and go through every circuit underneath there. If the actuator opens the vent with a little nudge I would suspect a vacuum leak in a line under there. I think you have to remove the dash to replace that actuator.

Dear senior member Jeepboy,

I've BTDT on the 123. If the center vent isn't opening, verify with a vac source, and prepare to remove the entire upper dash. You can get one or two fingers on it with the upper dash installed, but I've yet to hear of anyone who ever pulled it without removing the dash. That includes me.

The first (and hopefully last) time you pull the upper dash, plan on 4 - 5 hours for the r/r. Have replacement diaphragms on hand or be prepared to leave the car sit torn apart. I don't prefer this method because my memory for how everything came apart fades exponentially with each passing day. After three or four days, I'm relearning what I did on the disassembly.

Once you have the upper dash out, check all of your vacuum actuators (that's what I call them) and replace or repair any that are marginal. Some would say r/r any that are hard to get to at all, your choice. Also check the vacuum solenoids behind the switches in the center console. They aren't easy to get to, but they're EASIER with the upper dash out. They're nickel/dime parts that kill the system when they fail so check them also.

Before you put your dash back in, check all of your vacuum lines and connectors for cracks and disconnects caused during the job so far. When the dash is back in, check again. Also, there is a check valve in the very front of the dash behind the speedo assembly, all the way up under the dash surface when it's installed. Check that one too, it's a royal PITA to change with the dash intalled.

That's all I remember, I did mine over a year and a half ago. If you get stumped on the removal, you probably are missing at least one fastener. The dash doesn't need a lot of force to come out, just careful maneuvering around the steering wheel.

Good luck!

Thanks Jim, Mike. Looks like ill have to remove the upper dash. I hate to do this because i bought a dash cover for it from performance products and don't want to ruin that taking it off. Oh well ill see if it comes off easy without cracking it.