how much trouble to put ac back on?

here is how its done. drain the oil from the compressor. reinstall the proper amount of polyolesther oil. mount everything hoses etc. and use nitrogen to pressurize the system to 100 pounds. check after a couple of hours. if the pressure has not dropped than you are leak free. if it drops use soap on all connections and look for bubbles. that would be your leak. fix your leak and repressurize. check again. then evacuate the system and then charge it. using 134a refrigerant. of course you might want to make friends with a refrigeration/ac mechanic to accomplish this. instead of spending 400 bucks on **** you may never use again give a hundred to your buddy and get it done right.