The house
How to Leave the Air Conditioner When You Travel
What to set, what to turn off, and how to keep a drain problem from becoming a ceiling stain while you are gone.
Turning the system fully off in a humid climate is how you come home to a smell and a swollen door. Letting it hold 78 or so keeps the moisture down without paying to keep an empty house at 70.
Before you leave
New filter. Drain line not already backing up. Thermostat on cool, fan on auto, setpoint in the upper 70s. No 'hold' fighting a schedule you forgot. If a float switch has been tripping, do not leave until a shop has cleared the drain. You will not be there to notice the pan.
Tell a neighbor the house should not be silent and hot. A system that dies on day two of a heat wave is a pipe-sweat and a pet problem, not just a comfort problem.
What not to do
Do not set the fan to on for two weeks. Do not cover the outdoor unit and leave the system able to start. Do not assume a smart thermostat's 'eco' mode knows your climate. Read the setpoint it will actually hold.
Ready to call a shop? Find independent AC repair by city.