Here is another thread that reinforces that the gateway for the HVAC is the most likely culprit.
http://www.keystoneforums.com/forums...t=35941&page=3
I had to have this done on our 2019 29BHS, as well. After the job was completed and I went to pick up the trailer, I tested it before I even hooked it up to the truck. The technician had not ensured that the dip switches matched the old gateway, so nothing even tried to turn on. That was an easy fix. Then, there was the standard "sawdust in the sail switch" problem that seems to happen quite a bit. They kept the trailer over the weekend and fixed it on the next workday.
Just to be clear, the HVAC gateway and the iNCommand system won't play nicely below 40 degrees or over 100 degrees at the sensor on the wall without a new gateway.