Hello, I will try to help. Usually this problem is caused by a faulty A/C clutch. If the A/C clutch does not cycle when the vehicle gets to operating temperature, then I have hit the front of the A/C compressor with a broom handle before and the compressor will then kick in and the air will blow cold until the A/C clutch fails again. The repair is to replace the entire compressor assembly, as it takes some special tools to replace just the clutch portion and usually isn't anymore cost effective. That is one scenario. The other scenario is, that something is leaking, such as the compressor or evaporator. It would be a good idea next time you put any freon in it, to charge it with ultraviolent dye. Then if the A/C system does have a leak, you can find the leak easier when charging the system with dye.