[VetteVet]

Cliff,

I'm not understanding your question. Are you asking how to vacuum(evacuate) the freon system prior to charging?

If so, detailed instructions are available in the FSM. Pay careful attention to the type and quantities of oil. The FSM lists how much oil should be present in each of the components. There are variables depending on whether you are changing any components, but the FSM explains it pretty well.

Feel free to PM me if you have any questions. I do marine AC systems on the job and do all of my own AC work on my vehicles.

Jep