I got mine working on the '88 951 about 6-months after buying it last year. With winter coming on, there wasn't much motivation considering all the other more pressing maintenance and repair items need.
I had to a get a 90-degree adapter to make the low-pressure port on the compressor accessible. Added a can of R134a with dye to find the leaks. It lasted about 2-weeks and I found it was leaking at the inlet/oulet hoses on the compressor.
Let it run another 2-weeks to completely leak out and pulled off the hoses. Appears the O-rings weren't working any more, so I got 2 rings from NAPA that was compatible with R134a & oil. Installed those and filled it with a bottle of R134a+oil. Been working great for the past 7-months.
