Yes when going on Vacation it's best to leave your AC or air conditioner on if it's a central AC.
Leaving the AC on while gone and while on vacation helps decrease the humidity level in your home which helps prevent the home from becoming stuffy and moldy.
Mold growth can easily grow on walls and other parts of the house when the humidity level is too high so by leaving your air conditioner on while gone you help prevent that mold growth.
You don't have to keep the air conditioner on the same temperature you keep it on when home to stay cool.
But just leave the air conditioner on to where it will kick on to keep the house at least below 80 F.