rekstein

Just picked up a 1988 911 cabriolet last year and the a/c was inspected and working according to the report. Needless to say it wasn't this past hot spell. I looked inside at the compressor. I did not know if it was r-12 or r134 that is being a newbie. Having done some more reading and have found the gauges I bought to check the system are screw on which I now understand to be for an r-12 system. The fitting on the compressor are a clamp on type. Which I now understand to be for r 134 freon charge. Ya think there should have been a label somewhere. Having just purchased 6 cans of r 12 and reading all the posts should I switch it back to r12. And how do I know the system is truly charge with r134? and the o rings and the other stuff I read about was done correctly?. I haven't even got up to testing for leaks yet. Would appreciate the groups thoughts on my situation. Could have r-12 cans for sale soon. And a winter project on my hands. Thanks

rusnak

If it's been converted, then you have an easy job ahead. Gauges are easy to get, and you just need to rent or buy a vacuum pump and maybe some cheap o-rings to do the job right. If it's R-12, then your best hope is that there is some pressure in there, and you just need a can to top it up, but you still need gauges, which you might get on E-bay. R-12 fittings are black, and the 134a fittings tend to be red (high side) and blue (low side).

rekstein

yes the fittings are red and blue. so I guess its r134. will have to buy r-12 to r134 adapter fittings. Is it possible to have r134 fittings and filled with r-12?

rusnak

If it was my car, I'd hold on to the R-12. I'd get the system running and verify no leaks or blockages with the cheap(er) 134a, and then worry about converting it to R-12 later, like next year.

You don't know if the compressor is seized, or if there is a leak, or if the receiver dryer is blocked, or of the expansion valve is plugged.

When you do the conversion, see if the expansion valve has a stamp on it, and if it says "134". It seems there is some disagreement on compatibility of oil, and if you need a larger orifiice in the expansion valve for R-12. So I'd poll the experts on these issues in advance.

I would also plan on a full flush of the system if you find that it's been compromised. I found out the hard way that bits of dirt and metal can plug the system.