My roomie likes the heating, and likes it a lot

I don’t want to make trouble, really, but this level of heating at this time of the year is starting to drive me a little crazy

I was not excited about signing up to be paired with a roommate, but I had no choice. There is a local business that sets people up as roommates, and usually it’s people like me with no other way to make rent. I filled out a questionnaire so I could be connected with someone similar to myself, but I don’t think they used it at all. I think they set me up with someone totally random. On one hand, now I can make rent every month and won’t get evicted, but on the other hand, I really dislike this girl. She likes it hot, and keeps turning up the air conditioning every time I turn my back on her! As if that wasn’t bad enough, when I am not home sometimes she will even turn on the heating, and this is in May! Since we are roommates I can’t simply forbid her from touching the thermostat, although that is what I would prefer. I did tell her if she kept running the HVAC system so much it would make the utility bills a lot higher. She agreed to pay whatever overages we had on the bills, as long as she could keep using the thermostat as she wanted to. I don’t want to make trouble, really, but this level of heating at this time of the year is starting to drive me a little crazy. I wasn’t someone who ran the AC all the time, but when I am home I like to be comfortable and not soaked with sweat.
HVAC duct