For an R-134a A/C system, if there's a refrigerant leak, does the (PAG or ester) oil automatically leak out as well? (Mercury, repair)

[Zhang Fei]

In other words, if there's a slow leak, and the system needs to be recharged, does (PAG or ester) oil need to be added as well?

[M3 Mitch]

Short answer is it depends on where the leak is. If you can see the leak area, is it oily?

Sometimes it's better to drain the remaining oil and add the correct amount of oil when you are not certain how much is in the system.

[wheelsup]

You can't suck the oil out of the system though, my understanding of pulling a vacuum on the system just got rid of the 134a not the oil. You might be able to drain the oil in the compressor but then it shouldn't be leaking out anyway.

[M3 Mitch]

True, it varies by system. I think in general the oil is not usually affected much by leaks, but I don't want to say "Oh, no problem, just fix the leak and refill with 134a, the oil level is fine" since I don't actually *know* that.

[prettyprincess]

the reason you pull a vacuum on the system is to remove the water, the correct way to service an a/c system is to vacuum, flush with a nonpetroleum solvent, repair the leak draw the system to 25-30 in of Mercury add your lubricant with in injector then charge. if you do not flush your system it could cause compressor damage from to much oil in the system, never assume or guess how mush oil is in the system