A/c maintenance Traditional gauge setup using vacum pump to recover freon GAS?

I want to use my 3cfm vacum pump to pull all the freon GAS VAPOR from my a/c system the vacum has an exhaust port which can be routed via a line to a storage tank for later use.The plan is to put a 30hg vacum on the tank ,allow the tanks vacum to pull the gas into the tank, once the pressure equalizes between the tank and the a/c system turn on the vacum pump to get the remaining vapor into the tank. Can someone tell me if this will work?