>I have an '85 Westy with A/C.  What does the temp. knob do?  Does it
>control the cooling by cycling the compressor?  Is it tied to a bi-metallic
>on-off switch somewhere?

Most simple thermostats like this one have a common thermosensor,
which varies its resistance with temperature. This resistance is
compared with the resistance setting of the temp knob on the dash.
The difference in these two resistances determines when the
compressor clutch is activated.

>I would guess in a Vanagon, it is set on "Max" all of the time anyway.
>If this part of the switch is bad, could I put in a separate on-off
>switch to kick in the compressor?

Would probably work. But a compressor rarely is working all the time.
If it is, some A/C component is undersized for the job at hand. The
compressor life is reduce significantly if engaged "full time", I'd
think.

>How much juice does the compressor clutch draw?

Several amps (6-8?)

For those of you who live in extremely hot environments, a member of
a Mercedes mail list (He lives in Texas) has experimented with
putting a small resistor in series with the sensor (I think) which
lowers the achieve-able minimum temperature. Here's the link:

< http://hsb.baylor.edu/html/easley/autofaqs/etrnew.htm >

*** Please *** do not bother the web site owner with questions as
regards VW air conditioning. This is a topic he neither knows
anything about nor has the time to speculate on. He runs the MB list
and has plenty of tasks to occupy his free time.

Also, as regards applying this customization procedure to VWs, you
must be comfortable with doing some research and development with
electrical components; the ideas presented in the above procedure are
meant as an inspiration to your creativity, but the unique resistor
values will need to be determined via experimentation.

Dave

--
Dave Carpenter

Whatever you wish for me,
May you have twice as much.