GoWesty does a pretty good job of trying to explain heating and ventilation controls.
http://www.gowesty.com/library_article.php?id=311

Actually, I think all of their articles in their "Library" are worth reading.

Rich
San Diego

--- On Mon, 1/24/11, Mark L. Hineline <hineline@OCOTILLOFIELD.NET> wrote:

From: Mark L. Hineline <hineline@OCOTILLOFIELD.NET>
Subject: Such a splendid waste of time
To: vanagon@GERRY.VANAGON.COM
Date: Monday, January 24, 2011, 6:00 PM

Last night, on a short drive in my '82 Westy, I decided to turn the
heat on and warm my toes just a tad. I did it by feel, as the levers
were unlit.

This morning I decided to find out whether the levers for the fresh
air and heat are supposed to be lit. Thus began a spout of obsessive
behavior during which I pulled out the radio, the lighter, the
instrument panel, and the heater control face. I traced wires and
studied the Bentley until finally I found the wires and sockets. Then
I did battle with the bulb to make it light up. Six hours later I had
light behind the levers.

Now to figure out what the bottom two actually do.

Mark