i have a 94 camaro z28 i am wanting to get the ac system back up and running its all there nothing has been removed but was told when i bought the car that during a motor pull they unhooked the lines and let all the coolant come out and never refilled it and i have checked the lines are completely empty. what would i have to do to get the ac going agian is it as simple as throwing a vac on it and then putting coolant into the lines or does stuff go bad when left sitting empty. from what i have heard its been empty for about 6 months to a year. and i have been told it might need oil how do i know how much oil to put back into it