They already make something similar to what your talking about and sell it
various places.
The following comes from JC Whitneys online catalogue at
http://www.jcwhitney.com/productnoitem.jhtml?CATID=59031

AIR CONDITIONING/HEAT EXTENSION FAN
Direct warm or cool air to problem areas...like hands or feet
Great for defogging windows
Keep rear or front passengers comfortable
Tube clips onto air vent louvers and extends up to 42" to easily reach back
seats. Booster fan with on/off switch plugs into cigarette lighter and
maximizes airflow. Black impact-resistant plastic.

You would need to extend the tube about a foot to reach the front passenger
area and could wire the fan into the A/C blower fan or install a lighter
socket in the rear of the van somewhere.

Tim Hannink
Winter Park, Florida
Goldibox - 1987 Wolfsburg Edition Westfalia Camper

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf Of
KENWILFY@AOL.COM
Sent: Tuesday, April 10, 2001 9:53 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: 85 Westy A/C & Aux battery

I thought about the A/C question last year with a customer's westy.  My idea

was to use some PVC piping (square) that is normally used for guttering and
run these from the rear A/C unit up to just behind the driver's head.  You
could paint it to match the interior of the van and terminate it in a vent
that would allow you to control the direction of the air and also the
amount.
 I tested this idea last year and it worked excellent.  Haven't had the
chance to perfect this setup yet though.

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242