Although I have a 95 (which may not help you), I am dealing with this problem right now. My problem was not related to the heater coil, as it is just water. I had the evaporator box resealed, the replaced (because there was a TSB for a redesigned box. You may just need to have your evaporator box resealed. That fixed my problem when I first had the car in '98. Good luck.
