Yes, you need not add dye. I'm sure there is enough in the system. The yellow glasses do indeed help recognize dye. Sometimes it is hard to find and they help.

I'm concerned that you said that there was only two drops of condensation. Was it not cooling well? It would be nice to have a nice, fat puddle to look at in the dark with your bright light and yellow glasses. When the dye shows up in condensation water it is not as if the water was pure dye. It is in there in a trace amount. You need a strong light, yellow glasses and a dark area. The water will only glow slightly if the evaporator is leaking.

Good luck,