If the system is now fully charged and blowing cold with dye, don't waste your time or a techs by having him inspect it in a week as the dye won't be visable UNTIL the freon has leaked out enough to notice that it's not blowing cold again. At that time, one can remove the blower motor resistor (behind knee bolster) and visually inspect the evap with a black light. Yes, it's usually a leaking evap.
Sometimes the dye is not easily seen with the evap in the car as it can leak out from the very bottom so it's then hard to spot with it still installed. It'd have to leak ALOT to be visable from the moisture drain tube, I've seen that but it's rare.