A/C fitting size

[etc1006]

I decided to check my A/C last night. What size is the high side fitting? It's smaller than the line on my gauges. Car still is R12. I wanted to jump the pressure switch and get a reading of exactly how much I have left... I can hear a bearly audible hiss if I press the schrader, so I figure its got something in it... I looked around and didn't see any obvious leaks at the fittings. I have 1 can of R12 on the shelf(but need to get a tap), and the better part of a can of R134 from converting my Probe a few years ago... I kept the conversion fittings when I sold it as it all leaked out by the end of the summer. I grabbed an extra condensor I have and noticed it had the 134 fitting on it, then looked a little closer and noticed it was a conversion fitting. The condensor had been converted... Dunno what year it came out of. It even had green o-rings on it. Whoever had that one converted went the whole nine yards.

15:30 update - Well it seems that the slight hiss I heard at the schrader valves was either a slight vacuum or pressure buildup of some sort from checking the operation of the compressor... Not real concerned with the high side right now... Have a vacuum holding at 30" right now. We'll see what happens. I checked the fittings down by the compressor while making sure the compressor was okay and saw no oil either. One line had Goodyear stamped on it. I'm figuring that has been replaced at one time then. Maybe someone never recharged the system? Everything "looks" original though. As far as dirt rust on the metal lines, etc...

 

[etc1006]

Well, I've got the system pulled down to 30". Been holding so far. I'll leave it in a vacuum for a day or so then decide what I want to do. I have a whole 12 oz can of R12, found a tap for R12 @ AZ of all places (couldn't beleive it)! Then get the remainder off Ebay or something. Or I have just under a whole 15 oz can of R134 from the conversion kit. The probe took a little over 30 oz. so thats why this has a little less than 15 oz... The conversion sets oil have POE which is compatible (miscible) with the older mineral based ref. oils. PAG is the oil used specifically in R134 systems.
Also, for you folks looking for the o-rings, AZ has kits of them. A small one for ~$3 with like 24 of them. Then a big set for ~$20 forgot the number of pieces though, its alot.