you need the right equipment to to remove and re use the old freon, its a gas and will spray out when you bust the line off the compressor. if you go the let it fly route, dont breath it in. or you'll be pretty sorry lol

some shops will suck it out and store it for ya. might be cheaper then a refilling it. after they drain it you can go do your repairs then go back, they will have to vac test it, then if its air tight they can refill it.