Like others mentioned, I wouldn't worry about the heat as much as the humidity. I would not rely on the AC to do that as it's not as efficient for only removing the humidity. It does the job, but costs a lot more to do it.
I'd set a dehumidifier up someplace with a drain line attached to the tank so there was no emptying the tank, and let it maintain the humidity level as necessary. If there is no floor drain available, set it on the kitchen counter and run the drain into the sink.
We live 6 month (winter) in AZ and 6 months (summer) in AR. In AZ, we cut off main water line to the house, turn off fuse to water heater and set the ac on 80. If you leave the ac off, you can have humidity problems AND it can get hot enough in AZ to cause problems with the glue that is used on building cabinets.
We have someone check the house every two weeks and flush the commodes. If you let the water in the commodes evaporate, roaches will come up through the sewer line and you will have thousands when you return. Trust me on this, I am speaking from experience and it is not a pretty site. Also cover all drain and tub/shower drains. Very important.
In AR, having dehumidifiers in the basement is a must or you will have really bad mold problems, on everything.
And, not just the toilet but the sink drains can dry out too. Then sewer gas will back up into the house and stink like heck.