Couple questions; Why did you charge it in the first place? Did you charge it yourself? How much freon did you put in? When you say it isn't working, do you mean it is blowing room temp air? Do you know if the compressor clutch is engaging? Having asked all these questions, I will tell you that the best way to remedy an A/C system that is low on freon is to have it evacuated and put under a vacuum for at least 15 min. and then recharge the system with exactly the correct amount of freon as stated on the tag in the engine compartment. Of course, this will likely have to be done by a auto shop or dealer unless you have the equipment or know of someone who has it. If you can answer all or some of these questions, I will try to give you a better answer.