Newmar used Suburban back then, probably the SF 35. Is the Wall Tstat display OFF completely or you do NOT have it in furnace mode and calling that OFF? You have 2 Zones and Zone 1 is the furnace for the RV. If you have the Bottom black switch of the Wall tstat OFF, then the problem will either be the Furnace board or the front AC control board. IF you have it on Zone 2 and the Zone 1 has the furnace set to run, then that is your problem. Verify both settings on Zone 1 and Zone 2 are set to OFF. Doug