Hi Suzanne,  I recently converted my ac from the R-12 to the R-134 using the
kit from Walmart.  It works great so far and was simple to do.  Before that
the AC didn't work except to blow hot air!  I think that is the way to go.  
The Bentley has instructions on how to purge the AC system.  I was afraid to
do it at first but everything turned out well.
-Loretta
87 Syncro GL
90 GL