I think it was my own post early in that thread that introduced the word "plenum" into the discussion and I think I used it correctly. I'm no HVAC specialist (although I did install a complete unit with ducting and everything in my own house) and I learned about it doing that job, and the term carried over to describe the function of the A/C enclosure over the Westy back seat.

Does this sound right?�
http://en.wikipedia.org/wiki/Plenum_chamber�

Can't answer your question about the effect of going without that enclosure/plenum/device on the rear seat passengers since there's just the two us humans riding up front and the dog on the back seat has not yet complained, but it sho' do blow lots of cool to us up front.

Stephen

--- On Fri, 8/24/12, Derek Drew <derekdrew@DEREKMAIL.COM> wrote:

From: Derek Drew <derekdrew@DEREKMAIL.COM>
Subject: Duct-less Westy A/C Query
To: vanagon@GERRY.VANAGON.COM
Date: Friday, August 24, 2012, 3:40 PM

There are threads probably on here and at Samba where people are
taking the Westy overhead-of-the-rear-seat air duct (usually beige)
off the front of the A/C, something people seem to call the plenum
because it sounds cool.

Here is a great thread on
it:
<http://www.thesamba.com/vw/forum/viewtopic.php?t=424773&postdays=0&postorder=asc&start=0>http://www.thesamba.com/vw/forum/viewtopic.php?t=424773&postdays=0&postorder=asc&start=0

My question is about the practicality of doing this with respect to
the rear passengers.

Has anybody tried using a plenum-less setup where passengers were
actually sitting in the back seat????

What I am wondering about is whether the most important original
purpose of the plenum was to direct the cold air forward so it
wouldn't blast onto the occupants of the rear seat and have them
revolt or put on winter coats and hats.

I get complaints as it is from the people in the back that it is too
cold back there. Maybe VW felt that nobody would be able to sit in
the back seat if they didn't have something to duct air over their heads.

At 10:48 AM 8/16/2012, TJ Hannink wrote:

>Can the blower fans for the heater/defroster be used for the
>airconditioning
 evaporator?
>
>The part number for the front unit is 251 819 015 while the one for
>the A/C is 321 820 015.
>
>Physically they look the same and they are both rated at 300 watts.
>The only physical difference I can see is the electrical connections.
>
>One online parts vendor told me no, they are not interchangeable,
>another vendors website says that they are.
>
>Thanks in advance,
>
>TJ Hannink

_______________________________________________
Derek Drew
Washington DC / New York
derekdrew@derekmail.com
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