Yes they are vented though the front vents and the back windows only
There is a change in the heater ducting system which requires a dash
drop and a late model heater box to be installed first.
The removing the back window's and installing the short glass and vents.
All this to quiet the Van down??
Reinhard, you are the task master.
By just changing the door seals your not going to get what you think
your going to get.
Removing and reinstalling the doors is a real pain.
Especially the rubber boot for the wiring loom.
Getting it back in right is not easy.
Realigning the door isn't easy.
You'll chip the heck out of the paint on the leading edge of the door
before you get it back in the door jamb straight.
And the bottom line is the pipe piper has lead a bunch of people to
believe that this is the instant way to get quiet inside the Vanagon.
It isn't a miracle cure in any way, shape of form.
I now have a late model Van, and it's noise levels are no better no
worse than the earlier vehicles prior to me adding sound deadner's.
I do know that they have more padding in them than the early Vans.
This is really funny.
How you have lead so many, so fast into believing your "Theory" of how
to get the Van quiet with the installation of a rubber door seal.
You don't know this for sure but this�is what you have surmised and
your just thinking out loud.
Why don't you try it first, and then tell folks the uneventful results.

RC