I spoke with Advent and they said the only fix is to use the Air Distribution Box w/ Wall-Mounted Thermostat for Advent Air RV Air Conditioners # ACRG15. This will remove the Coleman from the equation allowing for the advent upper unit to communicate with the advent control box and the advent thermostat.
They go onto say that there is no way of troubleshooting the way the Advent, Coleman and Coleman adapter all work together, unfortunately. view full answer...