Something I do for grows that are pushing the AC to it's limits.
Get a lighting controller with dual trigger cords.
Get a high temperature shutoff. The Titan Zephyr 2 is an example.
http://www.titancontrols.net/shop/product/titan-controls-zephyr-2-high-temperature-shut-off-with-delay
Plug the Zephyr into the timer (may need an extension cord and a plug adapter to plug in one side of the controller as well) You end up with one side of your controller on the timer and the other side on the timer through the Zephyr.
Hang the temperature sensor at the canopy level under the lights where it's hottest, and plug the trigger cord for one side of the controller into the Zephyr.
Now set the temperature that you want it to react and shut down the lights that you plug into that side of the controller. It will have to cool down by 10 degrees before it considers the room ok so tweak your settings accordingly.
Set the start delay, this is how long it will wait after the room has cooled down 10 degrees before it turns the lights back on.
So lets say you set it at 90 degrees. If the temperature hits 90 it turns off a few lights. The AC catches up and brings the temperature down, then the controller waits the delay time and turns the lights back on.
This prevents you from frying a crop. You can pick the lights that are on the shutoff, in my case I have all my side lighting shut down, thats 3600 watts. I use a delay of 15 minutes. If it's 100 outside it will usually shut off the side lights a two or three times a day.
Note that when the lights turn on by the timer, the Zephyr will wait for the delay time before it kicks on the lights.