Chins need AC. They need to be at temps, 72 F and below, at all times. They can withstand hotter temps, sometimes... depending on the chin... but do you want to bank on the fact that your chin is one of the ones that can withstand the higher temps? I'd rather not.
I had someone drop off a chin the other day, and I put him in a cage, and she asked, "why do his ears look like that?" She was referring to being able to see the veins in his ears, more noticeably than normally.
This isn't my picture, but to illustrate:
That picture came from here, which is a page talking about heatstroke in chinchillas.
Now, this is my picture, and this is what ears on a beige chinchilla should look like:
When you see all those veins, like in the first pic... not a good sign. The chin is too hot, and needs to calm down. If I saw that... I wouldn't be taking pictures (the site linked has the picture for educational purposes, but I mean in general), I would be doing everything to cool down that chin and hope it survives.
Now, the chin brought in didn't look quite that bad, but I told the person, it was likely that he got hot in the box on the ride over. She then mentioned that she didn't have AC in the car, but had the windows open. Oh boy.
Now, while the windows open would keep the car from getting excessively stuffy, it doesn't actually cool the air, and I would venture that it was the lack of AC and the chin in the box for awhile that toastied up the chin. This all said, he's fine. But it was a moment where I thought, I should write about this, just in case.
I was also talking with someone who I'm shipping to, upcoming here, about temperature, and I asked them if they have AC in their cars. Now... the people shipping generally are a tad bit better off, money wise, as they can afford to spend (well, maybe not can afford to,... but they are spending) $200+ on shipping, so of course this person had air (they had a porsche and an infiniti, come on! of course they had air). But the point is... not everyone does.
If you don't have air in your house, you probably should not own a chin. A window unit is cheap enough, and does just fine... but they DO need it.
For car rides... if you don't have air in your car, please make me aware of this before you come to pick up your chin. We will schedule the time early morning or late night, so as to keep the outside temperatures as low as possible while the chin is in the car. A midday car ride, on a hot day, can easily kill a chin. We actually had two chins, years ago, Tic and Tac, who both died of heatstroke after being brought to the rescue, after being in a hot car with no AC for 3 hours. It's not a joke, they really do need their AC, so if you don't have, please advise. We'll work it out.