I can only reply to the A/C connector issue. We took delivery on a 2017 Sierra 378FB in late May. The day we were leaving the dealer the Zone 1 AC quit. They found a fryed connector (Looked like a telephone cord double female connector but different wiring inside) in the main AC unit. Replaced it with a new one.
Next day the unit failed again which turned out to be yet another fryed connector (same one). I did get the zone 2 AC to work for the weekend and on Tuesday morning after Memorial day we drove back to the dealer (2 hours).
I had sent them a email regarding the troubleshooting process I had followed over the weekend. I arrived at their shop about 10AM and they had already been in touch with Dometic about the problem. They were in the process of taking a control board off another unit on the line. Within 2 hours of our arrival they had replaced the control board (in the unit on the roof), found the connector fryed and had taken another connector off yet another coach on their line. We sat in their lot with the AC running full force until 5 PM to determine it was fixed. Have not had any trouble with the units working since.
The control board they replaced was burning the connector wires giving a E1 error signal to the thermostat.
Starrs Trailer Sales, Brockway, Pennsylvania are great people to do business with. All during the repair process they communicated the problem and were quick to find ways (to the point of making 2 new 2017 5ers AC inoperable to fix mine) to fix it.
Not sure if you have the same problem but it sounds similiar.
Enjoying God's creation each day.
2013 Ram Longhorn Laramie with 6.7L Cummins Diesel
Forest River Sierrra 378FB