Does using a vacuum pump remove any of the Pag Oil from the AC Compressor?

[William]

I just replaced my AC Compressor, added the right amount of oil and now ready to fill the ac with R134, watched your video on how to do it, but would the vacuum pump remove the oil in the compressor as well, or does it only remove air from the line?

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[Paul]

The pump shouldn’t remove or vaporize the PAG oil. The pump should remove air in the system, degas the PAG oil, and vaporize any residual volatiles (mostly water) from the system.

Rotary vane pumps typically release a small mist of pump oil from the exhaust port when it’s pumping against atmospheric pressure. Some pumps have a ballast valve to reduce the misting of pump oil. Also, water vapor will cause the pump to emit smoke from the exhaust port (actually, multiple things can cause the pump to smoke).

[Author]

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