well to keep this short, you need gauges to do a reading, to see what the system is and is not doing, then and only then can you actually figure out what the problem is.
This includes adding any refrigerant (its not freon, please don't call it that. if you don't know the right name, that's OK, just call it refrigerant) to the system, you may have been full already if that is not your problem, and you may have over filled it...
also, if you really were low on it, that means that you probably have a leak somewhere (and there is one that is quite common for the LS...), if you tried using it while it had a leak, you may have grenaded the compressor which could have destroyed the whole system...
I guess I'm also assuming(possibly incorrectly) that you have watched it and made sure that the compressor was running other wise you would have said its not even kicking on...