In line filter to protect AC programmer

[Leah Mueller <muellerl@cadvision.com>]

Dear Listers,

I have many good suggestions from you to help track down an occasional
reluctant climate control switching from warm to cooler to warm again.
There has been suggestions to put an in-line filter in a vacuum hose from
the engine to proctect the AC programmer from getting oil mist sucked into
it.  Does anyone know where this filter should be put and what kind exactly?
Also where is this thing called a Head control unit that also may get dirty
or oily and foul up the climate control capabilities. 

Thanks in advance for the collective wisdom that you have shared with me so
far. As I learn more, I hope I can help you in return.  I am fairly new to
Audi and learning to love them despite their quirks.

David G. Mueller
Alberta, Canada
1986CDt