@Jacqueline1270 That’s terrible; I’m sorry this is happening to you. How are the reviews for this place? Can you give us the link? Surely such a terrible odor would have been noticed by others.
Regardless of whether or not the host disclosed the heat situation, I believe there are certain minimal standards imposed by the city or other jurisdiction - something like “Accommodation must be kept at a minimum of 68 degrees”. Also check with Airbnb to see if that part of the listing description has been changed recently. In either case, you may be entitled to some sort of refund.