I added Freon, and it was ok. a little low but it didnt solve my problem. My Fan clutch was needing to be replaced, would that be the problem ? Though I would expect SOME cold air to come inside still. My truck's A/C also took time to get really cold at low RPM, I would basically have to be moving to keep it nice and cold. (This was all due to the fan clutch I assumed)
I already have the new fan clutch too...