Doug,
1. If the new thermostats are indeed programmable, it should have user-selectable functions to support logic in prior roof units. Windows 8 is backwards compatible to windows XP, which is the same era as the equipment in my RV. There is no excuse for Dometic forcing customers to essentially buy all-new AC units.
2. Mine does not have a heat pump so the heat pump thing is not an issue. But they should have had a way to either set the controller to at least emulate existing mohos with 2-speed fan so people with working units can still use them risk and all (If it dies, it dies, and until then why replace it?). One DIP switch or dip jumper on the thermostat to make the microprocessor emulate communications and logic required to run older units is all they needed to do. But they didn't do that.
3. My problem was with the temp sensing on the thermostat, which in my case is mounted on an insulated interior oak wall exactly 54" above the floor per dometic spec.
4. It took two days to figure out what to do, and two hours to install the new upper sensor on my board. It was the kind of technical challenge I latch onto when a lot of money is involved. Monaco was thorough and already had wiring for the remote sensor run down to the air intake. I mounted the sensor about a foot away on the ceiling, drilling through the foam to get there and puttying the wire into the hole. I always keep my fans running so the location of the sensor is not that important. I have tested it and it works fine.
It cost me a total of $20 for a remote sensor. Now anybody can do it for $20, and pay the local RV shop to do the work if they like. I have tested it and it works fine.
I have done many things over my career since 1974, including hardware, real-time software, mechanical design, autocad, laser cut metals, pneumatic controls, robotics, electrical panel design/install for projects in the U.S., Japan, Singapore, Korea, and China. I have designed automated panels and done PLC programming and MOSCAD systems for many small and large public wastewater treatment plants, and now work for a phone company doing automation for the biggest backbone on the planet. I do all my own HVAC and other work around the house for decades. Taking on one stupid undocumented dometic thermostat was not a big deal.
Since this Tstat has EEPROM memory, and resetting it improved the problem by 6 degrees, I am quite sure that one or more EEPROM locations controlling how the microprocessor interprets temperature pulses got mangled. EEPROMs are static sensitive and can be overwritten by static charges -- which is probably why they have the reset sequence to begin with. I'm guessing there are other undocumented button sequences to adjust how that works (to sync the tstat with its thermistor), but since Dometic isn't releasing any information, there is no way to guess what to do. It is also possible there are problems with the two chips on the board that handle thermistor to pulse converion, but shotgunning that wasn't worth my time.
You are throwing out a lot of wild theories, like hot LCD TVs and other diversions. Sure sounds like you are still working for Dometic. What I did works fine and cost $20. That is the bottom line.
