My question is when you vacuum down a condenser unit on a 3 ton do I vacuum out of the low side only are do I use both high and low side of manifold gage, my pump is a 6cfm yellowjacket. The same question for the recovery machine do I use the low side only are low and high sides both to recover refrigerant.

Well, think about it. You either have a TXV or an orfice somewhere in the line.

1. If you sucked from one side, it might take a long time to pull the refrigerent through the orifice.

2. Will any harm be done if you vacuum from both sides?

I'll leave you to figure out the answer.