Honestly I would just ignore the instructions and use the AC anyway. A dark room might be ok so long as it stays cool like 70F but 75F at the absolute max. Another option would be to find a place that has AC that you can take the chins to either a relative, friend, hotel or even a vet office that does boarding that have AC.
There are a few things you can do to help temporary, like I mentioned to you before in another post, freezing water bottles/jars and tiles and changed them out as they warm up/thaw, but that only works if they chin stays near them or on them. Not all chins will sit on cooling tiles even if they are overheating. You can also have the chin in a small cage and put that in the fridge with the door open, but will likely use more power then a AC and burn out the compressor in the fridge if done for long. Or drive around with the AC on full in the car.
