Autozen,

Everything you said seems to be right on the money. The only thing I would point out is that the York compressor in his 115 car does not hold up well at all to the added pressure of 134 (been there, done that.) Additionally the shaft seal in that compressor is kind of iffy when it comes to sealing 134. If it were a more modern compressor, your course of action would have lots of merit.

The York compressor based systems work great as long as they are kept with R12. It would seem to me that under his unique circumstances, staying with R12 would be the most economical and most effective thing for him to do, most especially since he is an area where 118 degrees on a Summer day is not at all unheard of.

My $0.02,