@Kari53 This would fall under extenuating circumstances. Don't cancel yourself, contact Airbnb and explain the situation and ask them to do a "neutral" cancellation, with no penalties to you. They may ask you to provide a letter from your service technician, or something like that. Also, contact your guests ASAP and explain what is happening, so they have a heads-up and can secure other accommodation, rather than being left high and dry last-minute. They may actually prefer to keep the reservation (after all, it seems posible that it could get fixed by then), and if they prefer to do that, you should offer a discount if the AC still isn't functioning, as well as sufficient fans to keep them from sweltering.