History: been to my mechanic 3 times over 2 years and AC still broken. He charges it a little and that seems to fix it, but then it only lasts for a few hours. I don't think it's loosing much freon and he can't find a leak anywhere. He has put dye in it several times and let it run for hours in his shop looking for leaks. He said it could be a small leak in the condensor inside the dash. Could it be a sensor that is bad that I can replace b/f replacing the condensor? Thanks.