Is this system still on R12? If it is 134, then the fan not coming on would be more apt to result in a high side runaway.

If you still have dye in the system and have it cooling, can you look at the condensation drain water with your black light? That's a good way to test the evaporator. It's hard to get a definitive test on an evaporator with a sniffer.

The next step in the leak check process would be to pressurize with Nitrogen and a few ounces of R22 then use a sniffer.