Insulate!
I run up to 90 - could be better lower, but 90 as a max that gets hit occasionally isn't going to kill anything. Try to keep things below 85 if you can. If you can't, another a/c is one option, adding insulation is another, and the last is... CO2!!! Yup, if you run CO2 you can crank your temps up 10 degrees... in fact, you SHOULD! But you must remember to keep up with increased transpiration as well, which means more watering and possibly more humidity.
Oh btw where is your intake air coming from? And do you run lights during the hottest part of the day? (11am-4pm)
Even in veg, making your 6 hours of darkness right around lunchtime and early afternoon is going to REALLY make a difference.