There's a great book called "Absolute Zero and the Conquest of Cold" that talks about medieval cooling using salts, and later with ammonia and other chemicals.

There's a great book called "Absolute Zero and the Conquest of Cold" that talks about medieval cooling using salts, and later with ammonia and other chemicals. INAS but it sounded like the key thing was circulation and ventilation. So if somehow you could keep a pump working, by crank, solar, wind, water, you could keep it circulating. Likewise to some type of air displacement.