I converted my '90 CRX Si to R134, When I had to replace the compressor shaft seal. I did have to replace the O-rings with ones that are compatible with R134. After I had compressor out I used compressed air to remove PAG oil residual. Honda has a conversion kit to go from R12 to R134, with PAG oil and fittings. Follow directions. The one thing it didn't mention was that the pressure relief valve needs to be replaced with one designed for R134. I finally figured out that I could use one from a car with a compressors like mine but a later year. I had to file down the flats on the Hex to fit in my compressor. The older valves are brass, new ones are aluminum.

I went through 4-5 original pressure relief vales before I took one apart and found seat material was breaking down from R134. The system would work great then about 4 days later charge was gone. After I changed out the pressure relief valve, No Problem. That was 4 years ago.

Either way it is going to be a job for a professional to get it completed - you and I can't buy R12 and an R134a conversion is a job for a pro. Even traces of R-12 will ruin PAG oil and there are a lot of conversion considerations. Usually the original big parts (compressor, condenser, evaporator) are kept but flushed and the dryer is replaced... the dryer is replaced whenever the system is opened.

I recommend calling around to shops for the price of a basic A/C service and approaching the ones with the lowest prices for guidance and non-binding estimates in doing it either way. As with muffler work, low price does not mean low quality but it does mean they are proficient enough to get the work in and out quickly. You will also get a chance to talk with them and you can get a feel for what it would be like to deal with them for the work itself.

Conversion needs all new if currently R12 system

If it's not been working for over a year it would be cheaper to buy a newer car!

Hi,

I am looking to get the AC in my 1991 Honda CRX working again. I took out most of the pipes and the compressor. The condenser and evaporator and dryer and the other part is still in. I was wondering if I should try and do an R134 conversion, or just stick with R12. If I were to do the conversion, how would I set about doing it? How do I get the residual R12 and the oil in the parts out? How likely is it I need a new condenser?