Performed diagnostic Sacramento. Found York furnace. Found that the Orignal thermostat isn’t working the way they would like. The back light is not bright enough, and it’s hard to set. To replace thermostat means you would loose the function of the smart vent. Replaced thermostat, removed smart vent control board and left in attic. Also left old thermostat in attic if someone ever wants to go back. Set up new thermostat for system. Re wired everything. Teated system