sounds like the technician is trying to make big bucks off of you. the problem is lint build-up that has clogged the drain for the pan. I just had the same problem with one of my rentals. first step is to remove the water from the pan. I then used a air compressor with a blow gun, wrapped a rag around the blowgun as a seal and used it to blow thru the drain pipe. heard a plop sound and now the drain is working good. part of the problem was that the renter had not change the air filter for several months and it had buckled from the incoming air, allowing lint to get to the evaporator and then wash into the drain. while there I also changed the filter for the renter.