Specific reading doesn't matter so long as you have a halfway decent
vacuum pump. Vacuum pressure should vary, depending on the
capabilities of the pump. It's not so important how strongly you
evacuate, but for how long you let it sit at vacuum. The vacuum
encourages water evaporation. After the vacuum is run long enough and
you've got most of the moisture out, you shut off the pump and make a
note of what the vacuum gauge reads. Check it after an hour, and if
it's the same, you have no leaks.

> What kind of Vacuum pressure am I looking for, prior to refridgerant?
>