Many have asked me about this exhibit under another thread, so I thought I'd switch to this one just to keep us organized 😉
Mona, I honestly don't remember if it was AC or not. It was not hot when we were in Paris, mercifully, so wasn't a factor.
I do vaguely remember feeling it was a bit close, but there were also many people ...but we were not uncomfortable.
Now that we are in Provence where it IS hot, I wish we'd planned to go to the carriers des lumieres here, which is in a grotto and apparently very cool - just a tip in case you are coming south. Although there are many more places I want to visit here so just as well; of course that was true in Paris also.
Sorry I can't be of more help. Enjoy!