vacuum pump

To remove water from an A/C system, we reduce the pressure in the system, thereby reducing the temperature at which water boils. At sea level, water boils at 212 F, but if we pull a vacuum of 29.40 in/Hg that boiling point falls to only 60 F. And if you can pull 29.86 in/Hg, water will boil off at a mere 10 F, for this you would want around 6cfm, this will be a top of the range vac pump
a 4cfm will be fine for general work, you would need to run it a bit longer thats all.

mark (mhpautos)