be careful my friend....never attempt to service a/c on the discharge side of a compressor. Is a very good way to hurt yourself, or worse. If you are feeling uncertain at all, maybe get some help. It is a simple task to service the system, but can go very wrong if you do not use the correct ports.
The line from compressor that goes to the receiver/dryer (where sight glass is typically located), is the discharge, or high side, of the system. So the other line at compressor is the suction, or low side, of the system. Many a/c compressors are actually marked at the fittings on back of compressor, but then again, many are not marked. One other clue is suction side lines are larger than discharge.
Also, did you find how you lost all of your refrigerant? If it is indeed all gone, which i assume it is, then you really should evacuate the system before recharging. That will also show you that you still have a leak (if system is unable to hold a vacuum). And add compressor oil to system when servicing too. Everyone seems to forget that part. If the r12 leaked out, so did a lot of the oil. It sucks to have a fully charged system only to have compressor come apart from lack of lubrication.
Good luck!
thank you plumcrazybee!!!!!!! R12 is very cheep, midwest swap meets thru the year 10 to 20 per can ,,,very plentiful if you look and shop the swaps,,,,,hit the jack pot at norwalk monster mopar last year case of 12 for 120 ,,,,,worst leak ever had on any car gm or mopar is needed one can per season,,,,also r-12 molecule,, spelling bad ,,is larger than 134,,, so any leak is worse if not corrected switch to 134,12 is also colder,,,that being said if r12 now then r 12 forever ,,,also have passed up buying full 25 pound cans of 12 ,,,,because cans so easy to find and use ,,systems with sight glass are great for do it yourselfers,,,,,,thanks for everyones input ,,,,lots of natural ac arround here below zero all the time ,,,,,gime some of that global warming!!!!!!
