Whether or not you should adjust your thermostat for a vacation depends on how long you will be gone. If it is a short weekend trip, keep your cooling system on, but at a higher temperature than you normally set it to. When you keep the AC running during short trips, it saves energy and keeps your home’s humidity level low.
If you will be gone for a longer trip (a week or more), you should shut the entire cooling system off.
If you have a programmable thermostat, you can put these preferences into the system and not have to worry about it. If you will be gone for a longer vacation, you can set your thermostat to turn back on the day before you return, so your home is cool and comfortable when you arrive.