Don't you love these good people on MAAST?!?

Rob, this is what we did when our AC went out for a couple of days at the end of August (~100 degrees outside)...

Opened up all the doors, hood, etc. to improve ventilation.
Ran three clip-on fans across the surface of the water 24/7 (2 over DT and 1 over sump).
Killed the lights for a couple days.
Froze around 20 1-ltr bottles of water to have on hand to float in the tank if temps got to 82.
Had JT's number handy in case we needed to take him up on his offer of a chiller loan.

Results:
We sweated a lot and did not dare leave our HOT house because we wanted to monitor the tank temps. Frequent showers recommended!
No problems with the tank, corals, etc. whatsoever.
Only had to float a bottle of water once or twice. Temp crept up to 81 on the second day and then just held there.

Good luck and keep us posted!