Fans do not do anything to cool a room - they simply improve air circulation.
Standards for care are universal - chinchillas are not suited for temperatures about 75 degrees period. Have some of them probably lived? Yes. Were they miserable, sick, weak furred, and skinny? Probably. Just because you can survive in conditions do not make them appropriate for continuous care.
OP, I would assume the mother is not coming back either from heat stroke, predator, etc. They need to be fed every 2-3 hours round the clock. And they should be moved inside. I am scared to ask if the cage is baby proofed - is bar spacing 1/2"x 1/2" or 1" x 1/2"? And the father of these chins...where is he? You will need to separate any female kits from brothers and dad at 7-8weeks or 200gs. They will and can inbreed. If you need help sexing the babies there is a sticky at the top of this section.