How-to
How to Get the House Ready Before a Long Trip
Do not turn the heat off if the pipes can freeze. Do not leave the air conditioner at 70 for an empty house either. Set one hold, then walk the equipment once.
Heat
For a winter trip, 55 to 60 is the usual hold. Low enough that you are not heating an empty house to 70, high enough that a cold night does not freeze a pipe in an outside wall. Off is how people come home to a wet basement. If the thermostat is also running a schedule, the schedule will undo the hold. Use one setting.
Cooling
For a week or two in summer, 80 to 82 on cool is enough in a closed house. Off, through a humid stretch, is how the house smells when you open the door. Put a new filter in before you leave. The old one will be finished by the time you get back and turn the setpoint down.
The walk
Nothing stacked on the furnace or against the flue. The outdoor unit is not under a tarp. If a humidifier is wired to the furnace, turn it off so it is not feeding a drain nobody is home to watch. Tell whoever has a key where the furnace switch is. The rest of a year-round plan can wait until you are back.