Sorry, but the GAST pump only pulls about 25.5, ac work needs 29.9"hg or better. The purpose of pulling a vacuum is to change the boiling point of water to 70F so that the moisture in the system boils off while you are pulling the vacuum. Of course this assumes that your working environment ambient temp is above 70F. of course you can help the process by warming the various ac components with a heat gun or hair dryer. Good luck!