My air conditioner only blows hot air. Contol panel is set to AC, but no cold air -- and I don't hear the compressor kick in. The car's air conditioner control panel was replaced about a year ago (apparently it was the last OEM unit left in the US). There are no blown fuses. Today I had the cooling system checked out by professionals and it passed all tests -- freon pressure is good, and the compressor comes on when given power from battery. Any ideas?