Your best bet as I see it is to make sure that any fins on the external component are clean(compressed air can be used to blow them out). If the fins are clogged up with dust or lint, then it won't be able to run. If the fins are clean and clear, then it's time to call around to hvac service companies. They'll be able to help you out with testing freon levels, and top it off if it's low(which will be caused by leaks) as well as possibly repair any leaks.
One thing to be wary of though is that the freon that is put in has to be the same type as it originally had, otherwise, you can end up doing a lot of damage.
__________________
|