r-12 sight glass reading?

Answer 1

It is illegal in the U.S. to retrofit an A/C unit containing R-12 refridgerant unless the sytem has a broken line, pump,etc. If the system is under pressure it must be pumped down by certified auto A/C technicians before the retrofit. It is a pretty hefty fine if caught discharging R-12 into the atmosphere. If the sight glass has bubbles running through, then it needs a charge. Good luck !

Answer 2

If the sight glass has bubbles or air that you can see its not full You should not see anything in the sight glass if you do its low
On R-12 if you are able to add till its clear or you can change it To R-134A its easy they sell the kit to change over at wal-mart
Its cheeper to than R-12 and easyer to get

Answer 3

sight glass is usually located on the accumulator/drier. with the a/c system running, you look at it and it looks like bubbles rolling around, it is low on freon, add freon until you no longer see this happening, at this point, you cant buy R 12 anymore, you will need to retrofit it to R134a. A shade tree mechanic can do this if they have the proper tools and understanding of how a a/c system works. But i would recommend that a reputable mechanic do this.