It's been a while, but I finally completed the project, or so I thought. After replacing the expansion valve, dryer, aux fan switch, pressure switch, manifold hoses and getting the compressor resealed I charged the system with 3 cans of R12 and got enough cold air to know that the system is working at least adequately. I put in 42oz. of R12 which is 10 oz. below capacity because I only have 2 cans left and the season is almost over. The bad news is that 4 days after charging I can tell that I've already lost some freon

After all of the work I've put in, I'm so frustrated that the thought of selling the car or rolling it off of a cliff would probably feel better than having a fully functioning AC system. There is a hissing sound coming from the expansion valve that started just today and I think that that may be the source of the problem. I ran my finger along the valve and the lines and no trace of oil. Any ideas? Thanks