I recently bought a used A/C compressor to replace the one that died in my 2007 Mazda 3. When I went to the auto wreckers to pick it up, it leaked a clear looking oily liquid out of the one of the screws on the corners that I assume are used to fasten the compressor to the car. The guy I bought it from said that's not a big deal and that he tested it and it works fine.

When I was leaving more of the liquid leaked out of it and onto my clothes. I rotated it so the liquid wouldn't continue to leak out, but it seems like there was more that could come out, so I want to know if I should be concerned. Should I return it, or should it be fine after its installed?

See photos of the compressor below

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  • It sounds like compressor oil (usually PAG oil of one sort of another). I'm not an AC person, but I don't think I'd worry about it too much ... other than you should replace it with fresh oil. Jun 22 '18 at 14:50
  • Thanks Paul. If it's leaking now though, wouldn't it continue to leak after I put fresh oil, or is it probably just because a screw is loose or something?
    – Pedram
    Jun 22 '18 at 15:05
  • Please tell me the compressor's model and brand so that i can have a look myself. Even better, post pictures of it and the liquid and screws you're referring to. Anyway, if that clear oily liquid (PAG refrigerant lubricant, often laced with a green UV dye so that any leak shows up better) isn't coming from either the refrigerant ports (which, on a side note, should be sealed right after recovering the compressor from the vehicle and checking its functionality) or an oil drain plug, that compressor is bad (it may have a leaking gasket or shaft seal, for example).
    – Al_
    Jun 22 '18 at 15:50
  • 1
    OK I'll take some pics this evening after work. The guy at the parts place rotated the clutch with his hand to show me that it was "good" because there was some resistance there. Not sure if that means anything.
    – Pedram
    Jun 22 '18 at 18:13
  • It doesn't mean a lot. Yes, the clutch hub of an healthy compressor, or at least one with healthy internals, is supposed to rotate smoothly with moderate uniform resistance (to understand what i mean with moderate uniform resistance: with my Delphi CVC, i can rotate its clutch hub with my little finger). The internals may still be good enough to not show any rough spot or seizure, but you can still have a leaking gasket or seal and in that case need to replace it before installing your compressor and having everything leak tested.
    – Al_
    Jun 22 '18 at 19:47

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