1994 Chevy S-10 AC works when it wants to.

When I start up to go somewhere, most of the time the ac will work fine. When I stop and start back up more than likely it want work. If I drive a long ways it will stop working also. I bypassed the cycling switch when it had quit and that didn`t work. So it`s not cycling switch. Tryed to put freon in it but it didn`t seem to take any. So what do you think? Sorry I can`t afford donation, i`m on ss and all credit cards are no good. Please help.