There is a seal in front of the compressor that can leak but normally that happens so slowly the mechanics have a hard time finding it with electronic leak detectors. There are gaskets too where the parts of the compressor body are bolted together but I've never seen those leak. A leaking hose would be fairly common but all you're going to see is the oil residue, typically right next to where the metal fitting is crimped to the end of the rubber hose.
Escaping refrigerant will vaporize instantly. It can look like water boiling, but if it's coming out that quickly that you can see it, the entire system will be discharged within minutes. There will be heavy frost buildup around the leak too. Most refrigerant leaks are much slower and take days or weeks to discharge the system. For leaks that small your mechanic can add dye to the system. Later you search with a black light. The leaked dye will show up as a bright yellow stain that you follow back to the source.
Sunday, July 1st, 2012 AT 5:23 PM