The F/I system is designed to increase RPM when the AC is turned on in order to
provide the additional horsepower required to handle the AC load. Sorry, I don't
know what that RPM increase is supposed to be, but more RPM basically means more
HP. Another thing you may encounter during really hot condition is the auto
matic shut down of the the AC. This mechanism is provided to reduce the load on
the engine during really hot conditions to prevent the engine from overheating.
By shutting the AC off, the need for the added HP is eliminated, and the engine
therefore runs cooler.

John Rodgers
88 GL Driver

Hans Roos wrote:

> Hi All,
>
> I just installed a new idle control valve on my 90 Vanagon to cure a cold
> stalling problem, it handled that problem perfectly!  Now something new has
> popped up, it idles fine until I turn on the A/C, then it immediately climbs
> to 2000 rpm.  If I turn off the A/C it drops to its normal idle at just
> below 1000 rpm.  Also, upon startup it hovers at 2000 rpm for a brief moment
> before it drops down to its normal idle.  Any ideas or suggestions?
>
> Hans