I tried deepwater and grew in an unheated outbuilding. The water temps probably ran around 50 degrees and the plants loved it. That said, I wouldn't do that in phoenix. The key to DW is dissolving lots of oxygen and the key to dissolving lots of oxygen is low water temps. In phoenix you are going to be fighting heat all the way, especially this time of year. If you must do this, try using powerheads to add oxygen to your water. Much better than airstones. You can get them at walmart, petco etc. There is an input on them where you can hook up your air pump, this pumps in even more air and makes them quieter.
Rule number one in the desert is run your lights at night, what little night there may be. With the AC I think you want to suck in to the cool tube and vent out. You will need to keep as much of the cool in as possible or you will be growing $5K pounds. When winter comes you will be styling since in PHX you won't have to worry about your plants freezing without heat. As I mentioned, if you can get your water hella colder than you think plants would like, they actually love it.