we've had summers without ac and the snakes have coped about as well as we have
I've given them refrigerated moss hides on really hot days; just make two plastic food storage container with damp moss and a hole somewhere for each tank and you can trade them in and out of the fridge or freezer; the snakes usually figure them out pretty fast; first they just lie next to them, later they move in; if you insulate the tank a bit, the cool stays longer; I tape those blue foam insulation tiles from the frozen rodent shipments around the tanks
frankly - we only got ac when I used to have tropical fish and realized that for the price of a couple aquarium chillers we could all be more comfortable, but now that there are no more fish, we hardly use it