VW Vans and Vanagons came with a wide variety of Port Of Entry A/C units.
Some have a low freon switch on the dryer or later models have it hidden in
the left rear pillar cover where the hoses go down into the engine bay. If
your freon pressure is low this switch will not let the compressor run
because it's the freon that carries your lubricant.
You can also have a high pressure clutch cutout switch similar to the
picture.
You probably need to check your high and low side pressures while the unit
is operating properly.
http://www.engineceramics.com/vw/acpressure.jpg
You'll be looking for something like this.
It may not have the plug, it could be another color and some POE installed
systems didn't have the switches.

Stan Wilder

----- Original Message -----
From: "Bike Florida" <bikeflorida@EARTHLINK.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, May 09, 2004 10:10 AM
Subject: Air Conditioner woes

> Well let me start by saying that my air is very cold, if it works.
Yesterday
> it just up and quit, today I looked it over, there are two wires going to
> the compressor, a red and blue one, and a brown one, then off the plug is
a
> smaller wire. The red and blue one has power, the brown one does not. The
> small one seems to be attached to the idle adjust when  the air is
running,
> and this works as well, after a lot staring at everything today, the
> compressor just came on, and it worked for a while, after I turned the van
> off and it cooled down a bit, it quit again.
>
> Any ideas, that in advance for any help
>
> Jerry
>
> '87 Vanagaon 'time machine'