I've come to the conclusion that we have a leaky fresh air vacuum element. Has anyone done this before?

How can I identify which element it is while laying on my back under the dash?

What color vacuum line is it? My Haynes book doesn't have a vacuum diagram.

From the shop forum parts link I found:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?clientid=catalog.mercedesshop&cookieid=1YB1110PK1YB1115RE&baseurl=http://catalog.peachparts.com/&partner=mercedesshop&year=1995&product=O4010-99492&application=000444865

Which gives us this photo:


I see two vacuum connections. Does anyone happen to know which is open and which is close? I'd be happy with fresh air all of the time and would like to just plug the vacuum line and wire the actuator open. If I ever have the dash out I'll replace the element, but I don't really want to remove the dash for just that one element.

-Tad

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1995 G320
2003 C230 Kompressor Coupe
2005 ML500
2007 ML350