I have a 2000 focus se. I've been having a/c problems with leaking refrigerant. I took it to a shop the other day and they said they couldn't find a leak but after they filled it up they said it's only blowing out of the two passenger vents. The drivers side vents blow hard but only coolish air. Its the same for the defrost. One side is cold, not the other. Ideas? Is it something I can fix myself. I am semi mechanically inclined.