Does anyone leave the AC on for pets while you’re out?

Honestly I can't say I officially *own* this cat yet. At first, it just hang around outside my apartment, and I feed it sometimes. Then I started seeing it every day when I got home. Last week, it suddenly jumped through my window into my room, really scared me!

Since then, it’s basically been staying at my home and refuses to leave. I guess I’ve been chosen. A friend gave me some cat food and litter, but I'm still hesitating about officially adopt it. If I decide to keep this cat, I think I have to leave the AC running 24/7, since it’s been hot lately.

Does anyone know roughly how much that would increase the electricity bill? That’s exactly what I’m worried about. Thanks.