Taking care of this

When my sister Polly is on break from college she stays with me. Polly gets into too many fights with our mother, and my brother and her are like oil and water. So I was the lucky winner that gets Polly for brief and sometimes extended breaks. My sister is just real young acting and totally unaware of what is going round her. I am trying to correct this behavior though. What drives me bonkers though, is that she leaves my air conditioner running all of the time. Polly will turn on the AC unit as she gets ready for the day, then will just leave. She won’t turn the AC off that high setting. Sometimes she will even leave the windows open with the air conditioner on too. That I can not tolerate. This is so bad for my cooling system. If you allow the hot air to roll in and the air conditioner’s air to leave the house, achieving the temperature on the thermostat is next to impossible. The air conditioner never gets to turn off the then. The cooling system just keeps on working all day, and it will work at a harder setting. Not only do my bills go up, the cooling system is more likely going to need a large AC repair. If this behavior goes on, the air conditioner could even prematurely die. I refuse to cut the lifespan on my air conditioner because Polly can’t close a window. I need to train her that this is not accepted behavior. I should make her pay the extra costs on top of my energy bill.