Find the leak and repair it using hi-grade epoxy according to package directions.
Pull down the atmosphere to as near negative 30 psi as you can. Close valves and see if the needle moves on the vacuuming job and repair you did. Needle drops to 0 you have a leak and need to start over. Vacuum holds? Good you have the leak fixed next charging the ice box: You should have your vacuum pump connected to your red hose, your freon attached to your yellow hose, and your blue hose connected to the low side/suction side of the compressor. You know this because the larger line coming off the compressor is the suction line, the smaller line goes off to the high side we don't need to go there. So we have vacuumed and close all valves and the vacuum is holding. SLOWLY open the blue valve and freon and let the gas equalize. Turn on the machine and SLOWLY put in gas until you have 5psi. And it stays at 5 psi any more and you will choke down the compressor. Ice will form on the compressor ear a sure sign of overcharge. Over charge is just as bad or worse than undercharge. Remember you are only gonna use 1/3rd of a 12 ounce can on most ice box's that use R134A. Get the needle on the blue gauge to stay at 5PSI and you are done!