30DS with Arctic Package Thermostat Question

[BatesMotel2]

We have a 30DS with 2 Atwood RTU's and trying to figure out if the thermostat may need replaced or re-calibrated? When we set it to say 70F, the furnace will not kick on until the thermostat ambient temperature reads 67F and will not shut off until it reads 73F. A 6 degree window seems to be a lot, anyone else experience the same??? (see pic thermostat type below)

[OldGunny]

Mine is a 2016, single AC, and yes, there is a pretty big zone with it. Also, it has the same "looking" cntrl pnl as yours.