To place an A/C system under vacuum and remove (boil) any moisture. Evacuating an A/C system has nothing to do with cleaning or flushing; it is simply placing the system under a vacuum to remove moisture.
To create a vacuum within a refrigeration system for the purpose of drawing out air and moisture. The system may be evacuated as part of a refrigerant recovery process, to check for leaks or to purge the system of unwanted air and moisture prior to rechar
To empty. Used in relation to cleaning Dewars or cylinders prior to refilling them with pure gas. Cylinder evacuation is usually done by drawing a vacuum with a vacuum pump and mildly heating the cylinder to expedite the evacuation. Pure evacuation cleaning can take up to two days of continuous vacuum so an alternating cycle of purging and evacuating the container is recommended.