LW1: Is something else going on with your daughter?  I've seen parents and children who had pretty contentious relationships, but it never came out of nowhere (despite frequent protestations, usually from baffled parents, that the behavior was totally out of the blue).  It's not impossible that there might be something medically wrong with her, but it's very unlikely, so either, yes, you did raise this, or there is another source of stress that you don't know about or aren't admitting to yourself.  

Re: The air-conditioning.  Even if it's cool, the air can be stale.  Install a ceiling fan.

So: Do you constantly compare her to her brother?  Could somebody be harassing her at this internship?  Do you harangue about her grades, threaten to withdraw tuition if she doesn't do things your way, otherwise hold her education over her head?  Did you spoil her when she was younger"?  Are you holding an adult to a kid's curfew because she's under your roof?  Listen and ask before you punish.