I can presently only get defrost heat, so I want to troubleshoot the vacuum actuators on my 300SD. Unfortunately I do not have the relevant volumes of the service manual.

What parts of the dash and/or console do I need to remove to gain access to the vacuum elements and any rubber connectors on the vacuum lines?

Does anyone know of any online diagrams of this vacuum system?

Thanks,
RayG

__________________
1985 300SD, 203,000 miles, dark blue

Lil Sarah says: "Poor old Grandma Blue Car...She's sad."

Hey Ray,
Try looking through some of these posts

Danny

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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I spent some time with the search tool and read quite a few posts on fixing the duct flaps/doors on a 126. I guess a better way of asking my question is:

How many vacuum actuators are there and in general terms, where are they and any critical tee or Y joints located?

__________________
1985 300SD, 203,000 miles, dark blue

Lil Sarah says: "Poor old Grandma Blue Car...She's sad."

Hey,
Sorry about the link. I'm no expert on this but I'll give it a shot. from what I've seen and read in these forums all the actuators are in the center console except for one above the glovebox I think.
The key to getting into the center console is the ashtray.
Click here for instructions on how to remove center console

This link may also help you:
http://interior.articles.mbz.org/123vents/

With a mity-vac and a little patience these actuators shouldn't be too hard to find and troubleshoot.

Danny

PS. found this in the DIY section:
http://www.ultrahot.com/vacuum/heating_ac.jpg

Vacuum Diagrams

Hope this help you.

__________________
1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination

You can access the vacuum valves by removing the carpet on the passenger side of teh center console. Of course to pull this piece of carpet you have to pull the under dash kick panel and then the floor mat. There is one screw holding this piece of carpet in place (the carpet that covers the tunnel up to the center console on the passenger side) and it is located about three inches off the floor and a couple of inches back of the firewall. it screws into the tranny tunnel. There are also a couple of tabs that fit into slots on the center console at the back edge and the very top edge where the carpet fits under the console surfaces. By pulling forward (toward the firewall) they will pull loose and you can twist the carpet out.

Once you have this removed you will see all of the vacuum valves in a neat row right next to the center console. You can test almost all parts of the system from right there which beats having to pull the console for this work.

Get a bag of golf tees because I can almost guarantee you will find some pods that are leaking. I just plugged the bad ones until the weather warms and I have time to take the dash apart ...

Once you isolate the bad actuators then you can determine the best approach to accessing them. Some are throught he glovwe box, others through the center console and some one at least is onthe drivers side.

One other note of caution, if you are pulling the center console on an 126 there is a cable that actuates the rear ambient air vents that lays under the console. It runs from the slide control at the rear of the console (at the vent) all the way up to and under the radio where the actual valve is. The book says to remove the cable end at the valve (under the radio) but I broke my connection there trying to undo it. (Thank man for inventing JB Weld) I found it easier to undo it at the rear but it is a b_tch to get back together. I was not aware of this cable until I couldn't figure out why the darn console wouldn't pull all the way out after removing all the parts that you normally pull/undo on a 123.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Fisherman is correct.

From each of the six vacuum relays, you can diconnect one at a time at the destination (pod) side and connect a mity-vac. Use the mity vac to test the ability of each to hold vacuum. The function of each is:

1) Defrost nozzle flaps
2) leg room flap
3) Center nozzle flap
4) Scoop air flap
5) Fresh air recirculated air flap and main air flap (small stroke)
6) Fresh air recirculated air flap and main air flap (large stroke)

Once you have identified where the leak is, (if there is one) you can attack the cause.

__________________
Michael LaFleur

'05 E320 CDI - 86,000 miles
'86 300SDL - 360,000 miles
'85 300SD - 150,000 miles (sold)
'89 190D - 120,000 miles (sold)
'85 300SD - 317,000 miles (sold)
'98 ML320 - 270,000 miles (sold)
'75 300D - 170,000 miles (sold)
'83 Harley Davidson FLTC (Broken again) :-(
'61 Plymouth Valiant - 60k mikes
2004 Papillon (Oliver)
2005 Tzitzu (Griffon)
2009 Welsh Corgi (Buba)