Are records harmed from no air conditioning?

Depends on the humidity. 90 degrees should not harm the records as long as it is not humid. If you live in Florida--well it's much hotter there so I'm sure that's not the case, but 90 dgrees with high humidity could create 2 problems. One is warping, which can also be avoided by properly stacking your albums vertically, snug--but not tight. The other problem with exposure to humidity for a long time is that records can get moldy--something to avoid. Hope you live in a dry climate--in which case you are probably alright.

TWL: When stored upright (with the end/back LP resting against a flat board) I have never experienced damage. I grew up in Iowa (no A/C), before moving to LA. Still don't use A/C (even removed one from our apartment as I hate the stuff in my home). The main problem comes from not having the back LP resting against a loose flat vertical surface that moves with the angle of the LP cover. Inserting a few more flat boards, in long runs of LP's, would probably be a good idea as well. Never had mold occur in living quarters, just basements and crude garages (not on a slab).

I did a move from the east coast to Arizona...in the summer! Temperatures must have reached 120-130+ degrees in the moving truck. All vinyl made the trip safe, happy, and unwarped. Don't forget, vinyl is shipped on trucks to stores (or to your home via internet sales) during the summer. Direct sunlight in a car is the real enemy (as I'm sure we've all found out through life's experiences. But heat & excessive humidity (real musty dampness) can cause mold, as Rives has mentioned. Happy Tunes!

clean them more often(preferably with Last all-purpouse liquid) than you would normally clean during normal temperatures/humidities.
keep them upright in polylined inner sleeves(audioadvisor)
so that the edge of vinyl is facing the upper edge of the jacket.