Two or three years ago my A/C refrigerant leaked out through the low side pressure value on the accumulator. After pulling a vacuum on the system, we confirmed it had no leaks, and an audible hissing sound could be heard coming off the low side valve. I (poorly) assumed the schrader valve was bad, bought some new ones, slapped them on, and refilled the system with R-12. Everything was great until today. I tried turning on the A/C for the first time since last summer, and the compressor is constantly cycling on/off with no cooling. I get home, do a visual inspection, and see a lot of oily residue on the low side cap again, with a little bit of a wet spot inside the cap.

This time I went to my service manual and learned the caps are supposed to have o-rings as the main seal since the schrader valves can leak. My caps do not have orings....which would explain why it seems I can only get a few years out of my A/C before recharging. My plan is to buy some o-rings, pull a vacuum again and if it doesn't leak, fill the system back up with the caps properly sealed. I'm having a hell of a time finding a kit or the sizes of the orings I need for the high and low side. Anyone know them or what to look/ask for? This is still an R-12 system.

Or is buying new caps the way to go like the ?