I looked at a 1989 PS31 a few years ago that had A/C installed but I don't remember the brand. The unit was installed in the locker aft of the head and accessed through the wooden louvered door above and behind the toilet. The cooling water was in fact t-ed off of the engine raw water intake and the discharge was stbd abeam the unit just above the boot stripe. The cool air outlet was on the shelf over the cabinet located between the chart table and the head. The outlet itself was a wooden box about 10" x 10" x 10" with metal louvers. A very nice installation and it cooled the cabin down in minutes.