John,
I have installed a prototype valve that shuts off all flow to both
heaters in my 2.1.  It is installed in the heater hose near the
driver's side driveshaft.  I made it out of CPVC because it was
cheap.  I know that material is not compatible with the coolant, I
will take it out promptly.  Probably will make the final version out
of copper unless someone points me to a better choice at a similar
price.  I used a 1/2' ball valve with about 3" of 1/2" pipe sticking
out of each end.  Cut the hose and stuck the pipes into each end and
secured with 2 hose clamps on each.  Works great.  You do have to get
under the van to switch it on or off, but for the really hot part of
the year that is probably fine.  It is pretty easy to reach and do
without getting dirty if you lay down your piece of cardboard or tarp
that lives between rear cushion and engine cover.

Neither of my heaters turn off completely.  I don't notice it until
it is really hot.  Even though there is no air moving past the rear
heater it heats up the whole underseat cabinet and bed area if I
drive  a few hours.  Not cool for sleeping.

Edward

At 07:46 AM 6/24/2011, John Rodgers wrote:
>  I need to install a summer shutoff valve on the hose to the front
>heater core. I just cannot get the heat valve to close tight enough, and
>in this summer heat hot air blowing is a bit much. Is this procedure
>posted on a website anywhere? Got a link?
>
>Thanks,
>
>John
>
>--
>John Rodgers
>Clayartist and Moldmaker
>88'GL VW Bus Driver
>Chelsea, AL
>Http://www.moldhaus.com