[boxcar]

Thanks for that info Andy. I'm backed into the drive at my farm garage and not level at all so I can't do the same measurement you did.

I had to wait for dark and used my laser level to determine that the top of my front Mach 15 is 10 inches higher than the top of my rear Mach 15. That will put the camper at a semi-trailer height, 13'5". Of course I need to verify that when my camper is on level ground - probably out at the barn where I have a 15' high door.

I'll sleep better tonight believing that I'm not too high for standard overpasses.

I worked this afternoon on the main A/C. The endoscope revealed that the air ducts are all intact and I didn't see any significant issues. The metal tape is actually quite well done in the circular ducts. As others surmised, my plenum between the intake and exhaust needed work as there were some holes, but not the major cavity that others have reported.

The biggest issue was the cover built by Coleman (now Airxcel). The foam inside was fairly messed up. I replaced it all with rubber foam of a similar thickness.

Interestingly, the fiber board blocking the supply from the intake needs to be slanted to keep the maximum opening for the supply to the air ducts, at least from the position that my panel is screwed in. But I got it done and the air flow is great - now I have to maintain my objectivity because I'm convinced it's working right. I cut one of the grandkid's styrofoam noodle to block the air duct that goes past the front vent - he won't miss the 8" until next summer.

The nice surprise is that I kept the camper at 78 degrees throughout with only the new bedroom Mach 15 on high cool and a fan blowing into the living area. High of 90 today, but having the backup A/C could make a difference if one fails during a camping trip.

With the 50amp circuit and both A/Cs running, it's too cold. I'll test tomorrow when it gets hot again, but I'm pumped!

One oddity - the Airxcel thermostat reads the temperature that I measure at the top of the thermostat housing, and that's a good 3 degrees warmer than the wall next to it and the bottom and sides of the thermostat housing. That skews my earlier testing as I'd never noticed it. Does anyone else have similar differences on the thermostat?