Evaporator leak problems are generally uncommon and are particulary uncommon on Contiques. It is much more likely that the problem is something else. There is a know problem from the insolution material around the dryer holding moisture and causing the dryer to rust through.
Refrigerant leaks are sometimes very hard to find. If nothing shows up with the black light, you may need to gain access to the evap core to inspect it with a black light. Another often successful way of checking the evapcore for leaks is to charge the system and park it overnight. In the morning have the sniffer leak detector pushed into the center A/C dash vent and turn on the blower as low speed and see if the sniffer squawks. You must leave the car windows up, preferrably inside where there is no significant air movement, disturb the car as little as possible, open one door only and keep it open as short of a time as possible, and do all you can to keep the refrigerant from disappating before you get a reading.
