I'm in the same boat as you. I converted my system to 134 which is a potent greenhouse gas but does not bust the ozone like R12. Then my second compressor died after 2 1/2 years. It was a Seltec rebuilt in China that I got on eBay for $100. I got another but new this time from a company in Arizona that was cheaper than FCPGroton, itself a very good company. The Arizona company advised my to buy an R12 compressor because it has two ports in the back for testing. On 134 systems, the two openings are already in the system in diffferent places. These people advised me to take the R12 compressor and drain the oil out of it when it arrives and replace it with PAG oil if it is to be used with 134. They also told me to replace the reciever/dryer as some metal from compressor death may have gotten in there. I got that part from Groton. I'm not sure of any on this but I pass it on. I have replaced the compressor, condensor, evaporator (turned out to be not necessary) and converted the o rings to 134 types and still can't get it to work.

Unrelated note: There's an air intake horn of some kind mounted against the driver's side of the condensor. This horn although made of plastic, rubbed a hole in my condensor over time. Check it out