Seems the Escondido paesans were having a bad Monday when they installed my AC. Upon disassembly, I found that the roof was reinforced in the area of the AC but not correctly. Pictures of the roof opening indicate to me that 1) plywood pads glassed to exterior skin were located too far aft, or 2) pads were located to spec but the AC opening was located too far fwd., or 3) the swale in the outer skin was intentional. I can think of arguments for all three but the fact that the gasketing surface was not a true plane or "stool" as was done for the front vent in the Burro
meant that even compression of the gasket was impossible to achieve. It had been tightened to the point that the gasket was completely compressed in front; barely compressed at all aft. Apparently it continued to leak as someone had added two silicone dams or levees outbd. of the gasket. The first of these was obvious when I bought the trailer and I removed it when I first began to refurb the trailer because I knew it was a hopeless lick and promise fix and removing it would reveal just how bad the leak was. Oddly I did not always get water in the inner pan in light
rains but did get some in protracted rains.
I had not had the inside pan and shroud off until yesterday. I could see the smashed gasket (pic #3) so I did a bit of pricing. What I could see from the inside was the partial reinforcement and the "step" in the external skin on both sides (#5). That made me think I needed a gasket thicker in the front. I wasn't about to spend 30-40$ for two closed cell gaskets so I got the idea that the closed cell polyolefin sleeping mats sold at Walmart might possibly make a reasonable gasket. #4 is the gasket material cut into several gaskets (I did not use them all) and #9 is the assembled gasket composed to two complete half inch thick rings and a third partial ring to give the differential thickness forward of the step in the skin. These were laminated using contact cement. The partial ring was placed on top so that the continuity of the bottom layer of gasket was not affected. While removing the compresser unit on top, I discovered that the flange in front and at sides was a bit hard to break free due to a second silicone dam. This was a lot of fun to remove with putty knife, razor blade, piece of plastic laminate, Bestine and scrubbing with coarse ScotchBrite but I knew that from getting rid of the first one over a yr. ago. Fortunately, this is about the first day with low humidity and decent air quallity we've had in three weeks so I took advantage. Pic #s 7 and 8 show the gasket from inside the trailer and from left side exterior.
Checked out dry with a good flooding of water from hose. Amazingly, that "step" at the sides of the opening creates a swale fwd of the unit which drains very well over the sides of the Pullman roof. One might almost think it was intentional altho when on the scafford it looks like a case of tincanning. I think my occasional leak was more due to the silicone dams than to this sorry excuse for a gasketing surface.
In the course of flooding the roof, I also got my half a cup drip from the upper part of the clamp ring on the rear window. I was already considering rebedding it but wanted to eliminate a leak between skins as the source, which of course led me to consider redoing the AC seal.
I find it odd that flooding without a pressure nozzle on the hose is a much more reliable and consistent locator of small leaks
than doing so with spray under pressure. I don't know if this is everyone's experience but it's mine.