Quetion specifically about air conditioning on buses

So yesterday I'm coming home on a north Philly bound bus. I get on in Center City. It's usually a double bus but we had a short one so it's a bit crowded even though it's a little after 8pm when I get on. However, it is warm out. And the driver doesn't have AC on. The roof window thingy isn't open either. It's stiffling. Now I didn't get a chance to ask if the AC was broken but before I make a formal complaint, what's the protocol on this? Are drivers required to have the AC on if it's over a certain temp or is it at their discretion? I know sometimes it may feel Almost Frigid on the bus but better to be cold than sweating and experiencing other people's funk. I took down the bus number and I want to know if I'm in the right to lodge a complaint.