One of the zone thermostats. If you have 3 zones, I think it's the center one. If two zones, I think the rear.
Coaches with Aquahot may be handled different than those with furnaces. Is there an Aquahot outlet (fan & heater) in the basement?
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC