I recently had my engine Replaced. The air conditioning worked fine for several weeks. Then one day there was no freon R134 and of course the ac compressor would not engage. I charged up the system and the compressor worked fine, but it leaked out by the next day. I then purchased R134 with dye, and used a black light to find leaks. I did not notice any right away, but it was day light. I drove the car around with the ac running and it actually was working fairly well even though I knew it was leaking out. That night I used the black light and was hoping to find dye on the rear where the seals are, and I checked the Evaporator, the lines, nothing. There was a tiny smudge of dye on top of ac casing which makes no sense . I found a vehicle in the Junk Yard were for 80 dollars I could grab the compressor with lines for 80 dollars. I don't want to purchase this as I am not understanding the failure. I have talked to 2 shops who want over a hundred dollars to evaluate this problem, and a 100 every hour they spend on it. My income is 1000 a month and I cannot afford that. Does anyone have any Ideas. I have read there is a special red UV Pen light, that will illuminate the dye better than the black light technique.

To confirm the failure, you may wish to drop another can w/ dye in there, and clean off the spot where you detected the dye before. You will also want to confirm that both valves are not leaking after the fill <a dab of water works wonders detecting these leaks>. Also check the condensor thoroughly, even the back side of it <you may have to take off the top radiator support to see back there>. If you are absolutely positive nothing is leaking there, the evaporator may be leaking. I wonder if it is, would you see the dye in the drain, from the dripping condensation.