Air conditoner is not working

Your problem may lay in several areas. First, it may be a bad a/c compressor. When you activate your a/c from the dashboard, does the compressor "kick on"? If "Yes", then lets talk about the refrigerant. When they added some, did it blow cold for a while and then get warm again, or was it warm immediately? And if so, what did the shop tell you as to why it wasn't blowing cold air? It could be you need more refrigerant (as they said the levels were low when they tested) because there is a leak in your system somewhere. You can determine all this yourself. Go to auto Zone or Advance Auti (or there west coast equivelents) and buy R134a recharge system in a can. Get the one with a dye in it. As you charge up your a/c, which hopefully gets cold for a while, the dye will works it way into any leaks. Then, after a day of driving with a/c on, thoroughly look over the entire system & lines. If there is a leak, usually at a coupling/connector, bingo, your problem is solved. Have it replaced, the system fully charged again, and you're off1