That suck, my last roommates kept turning the AC off. After six month, I finally had enough and taped the to the on position. You should explain to her to not turn the AC off. If you're leaving the house, then leave the AC on at 80F. If you have room, you should invest in a chiller as a back-up. In case she forgot and turn the AC off again, or your AC broke down while you're away.