W123 1985 300D - Center Vents - not working - never worked
 

Hi there,

My two center vents are not opening/working (#3 in picture below). I assume but will confirm this is the vacuum actuator. Can you guys confirm this is part #A 116 800 11 75 VAC. ELEMENT FOR CENTRAL NOZZLE AIR FLAP?

Is it best practices to replace all parts or is this the most common?

-A 116 800 11 75 VAC. ELEMENT FOR CENTRAL NOZZLE AIR FLAP
-A 123 800 32 75 VAC. ELEMENT FOR DEFROSTER AIR FLAP
-A 123 800 31 75 VAC. ELEMENT FOR LEGROOM AIR FLAP
-A 123 800 11 75 VAC. ELEMENT FOR MAIN AIR FLAP
-A 123 800 12 75 VAC. ELEMENT FOR CIRCULATING AIR FLAP

https://i.ibb.co/Xp15xZw/vent1.png

From what I've seen and read, the vacuum actuator is the most common problem. The part# you mentioned is what Peach Parts comes up with.
https://www.pelicanparts.com/catalog/SuperCat/3306/MBZ_3306_VENTAC_pg1.htm#item2
Several members recommend replacement of all vacuum elements at once, due to having to remove the dash to access them on a W123.

W123 HVAC Vacuum Elements
 

THANK YOU for the comprehensive listing of P/N's & the picture of which goes where :2thumbsup .

It can also be the vacuum switch. Only way to find out is to apply vacuum to the pod and see if it holds vacuum. If it held vacuum, then it could be the switch or the controller thats not working. If you already removed the dash, I would replace all the pods with new ones. The center vacuum line is also connected to the defrost pod. I glued my center flap open and disabled the switch and plugged the line.

HAVE FUN!! it is such an insane mess of crap behind that dash!

And you are gonna need a beer when you get it all back together and realize you accidentally disconnected a vacuum line or something and have to start over hahaha

I agree about replacing all of the vacuum pods now that you have the dash out. George Murphy at perfanalysis.com sells new diaphragms for the vacuum pods. They are simple to replace and a lot cheaper than buying all new complete pods. Be careful while removing the pods as the three legs (studs) can snap off easily. A trick that I found that helps while reinstalling the pods is to use a die and carefully thread the three plastic studs on each pod so they can be installed with nuts instead of the push on clips. The push on clips can be a real pain to push on. Vacuum pod number 2 is easier to replace if you remove the center console also.

-A 116 800 11 75 VAC. ELEMENT FOR CENTRAL NOZZLE AIR FLAP

NO LONGER AVAILABLE :(.

Help, I want to repair it properly and not prop it open!

How difficult is it to remove the dash?

That's something I've never done but I have the same issue, I'm just too scared to mess with the dash for fear of cracking or breaking something.:confused:

Actually, removing it is not all that difficult. It is the re-installing that is difficult.

W123 Dash
 

I wrote a set of instructions for the removal and installation of a W123 dash. It is about 3-4 pages long. Send me your email address and I am glad to send the instructions to anyone.

Having done 3 dashboard removals on 2 late model W123s, my obtained wisdom:
1. Follow the instructions in the Factory Service Manual.
2. Set aside a full day. Stated another way, be in no rush whatsoever.
3. Patience.
4. Take some pictures as the work progresses. Heck, also make a few notes to make life easier.
5. Categorize the experience as learning.
6. Enjoy realizing how capable one actually is.

As of 9:40 p.m. EDT today, M-B is selling 116 800 11 75 "Vacuum Element - Mercedes-Benz". List price $35.00 USD.

It's not available, the site just hasn't updated that it is not available yet.

If I ordered it, in a day or two they could come back and say NLA. I've already called multiple dealers.

Any ideas? Can they be repaired?

Please see post #6. The vacuum pods can be repaired and George Murphy has the necessary diaphragms.

http://www.perfanalysis.com/

This is an excellent source for many of the ACC related parts that are needed in these cars.