It is not just a 'set and forget' setting on your thermostat.  You need to understand why a functional and properly set A/C System is so important :

Detailed Analysis of Suggested Settings
 

The two biggest hot-button issues would be the proper A/C Settings and the Main Water being left ON / OFF to a home.

A/C Settings

Via FPL, with millions of local customers, their direction...which was re-issued and as follows for 2017, but mirrors the guidance that has come from us and / or local FL A/C Vendors:

http://www.fplblog.com/top-tips-for-snowbirds/ 

http://www.fplblog.com/ac-settings-away/

I leave Florida in May every year and return the following January. What should I set my thermostat on for the
summer? Should I unplug TVs, refrigerator, microwave, oven, etc.? I am also concerned about mildew.

Thanks for your question. Here are some tips to help seasonal customers – like you – maximize savings, and prevent mold and other potential issues while you’re away.

If you have a manual thermostat (most in PGA are of this variety) 

FPL recommends setting your air conditioning system to 80 degrees for detached homes and townhouses and 77 degrees for condos and apartments. These measures control the relative humidity (RH) in your vacant home by providing dehumidification to help prevent mold growth.

If you have a programmable (or WiFi) thermostat

A programmable thermostat is a more energy-efficient and effective option. FPL

recommends programming thermostats at 72 degrees for just two hours each morning before sunrise and at 88 degrees the rest of the time. This will help prevent mold by removing moisture from the air during the cooler hours, when relative
humidity (RH) is highest and your A/C runs most efficiently.

Energy efficiency tips

• Always set the A/C fan switch to the “auto” mode.
• Ceiling fans are not necessary since your A/C already circulates the air.
Mold prevention
The most energy-efficient option to help prevent mold from developing in vacant homes is to use stand-alone
dehumidifiers instead of the air conditioner.
• Use one dehumidifier for every 1,000 square feet of floor area.
• Set the controls to 58 percent RH, and locate them by the kitchen sink or bathroom shower so water from the drainage tube can go down the drain.
• Keep the doors to each room open to help the dry air mix with other air throughout the house. A floor fan set on low speed can help circulate dehumidified air to other rooms.
• You can add timers to the dehumidifiers and fans to limit their operation to 9 pm until noon each day.

Other ways to save while you are away

1. Save more by turning off the circuit breakers to the water heater and refrigerator. Make sure the
refrigerator is clean and you have a way to keep the door open while you are gone.
2. Unplug electronics to save money and protect them from lightning strikes during the rainy season. Remember, if it feels warm to the touch when it is plugged in, then it is consuming energy --even when you are not using it.
3. If you have cable or a satellite for your TV: When the TV is off, put your hand on the box that tunes the channels. If you feel any heat, keep it unplugged until you need it again when you return.

Other notes on A/C units
 

- We suggest you have a licensed professional service / review your unit at least ONCE per year. We always offer this service in Fall through House Check, if interested.

- This does not guarantee you’ll never have or experience an issue, but will help mitigate the potential impact of a major major or potential costly issues that could result. This is a great time to test the freon pressures and clean out the system drain lines and overflow pans, where equipped.

- Change your filters (at least) once per year with a high quality, pleated filter. 4 times a year is ideal under normal living conditions, but this exchange should be the absolute minimum, given the shorter service intervals that homes are also ultimately used in.  If you smoke, are in an area with a lot of construction, have pets or use your home a lot, you should consider replacing more frequently.

- When it does come time to replace your A/C unit, we always suggest you get 2-3 quotes from local providers, but make sure they are licensed and insured to install it.  

And though many will tell you differently, please PULL a permit for each and every unit that you install into your home.  This will protect you to ensure the work is being done correctly the first time, and if you go to sell the house one day, it will not come back to haunt you when someone goes to review the work / permits dones on your home.

Price by vendor can vary dramatically, especially depending on the promo’s offered, but please do not base your only criteria on LOW price either.  Can't tell you how many owners fall for this, and then eventually have major issues that we end up needing to call a professional outfit in to fix at considerable (more cost).