Bench test at Holiday World revealed that the AC is working properly. Problem is probably dirty coil. I told him that I cleaned the coil already. I took a closer look at it and sure enough, it was dirty down inside the coil. My attempts to clean it with a vacuum with brush attachment had made the surface look good, but I had just pushed the dust and crud further into the coil. I couldn't see this while it was on the camper, but out in the sun with the cover off, it was obvious. Hard lesson learned. I guess I'll clean it properly(with coil cleaner) and lug that beast back up and swap it out with the 7500 btu unit.