OK.. what won't cool..is the blower running? Has the freon level been checked? It's generally only a couple ounce's of freon for a system to stop running. Try going to parts store or even the evil Wal , buy a can of 134a with leak sealer or two, install (while running a/c) and see what happens. If it starts to cool, continue servicing.If you have a major leak it may be a line leaking,or compressor, evaporater. If it's minor the leak sealer might help. Did the system ever work?