I used to work in Menorca and we had villa reps who would hire out fans. If you have a rep they should be able to do this or point you in the right direction. Most of the villas are built for the heat anyway and so tend to be nice and cool inside. I lived in a villa with no air con for the whole summer and it was ok. If it is too hot you can probably hire a portable air con in Mahon at an electrical shop.