Service Hotline: Residential A/C Ideas, Connecting Circuits, Motor Sizing, Does Dry Ice Help?
I have some comments on charging residential a/c. This relates to previous discussions of this topic. It is correct that charging by just adding 30°F to ambient will not yield a correct charge on most systems. The correct use of this rule of thumb is to add 20° for high-efficiency, 25° for medium-, and 30° for older, low-efficiency units.
But this only gives you an idea of the range the head pressure should be in. It is not the way to charge a system.