AirBnB has no central AC, summer heat. Advice on upselling?

[Andrew Wong]

My units have no central AC. I clearly mark there is no AC as an amenity. There's been some heat waves in the area, two weeks ago hitting > 100, this past week hitting 85. 

Guests have been complaining about the heat, about it being unsafe. We provide a tower fan, but no portable AC unit.

We're thinking about buying portable AC units, but are looking for tips on how to monetize it correctly. Does anybody have any ideas?

Some include telling guests that they can rent an AC unit from us. But we can only have those units that have a hose out the window, installation on every turnover will be a pain.

Of course the other idea is the less painful thing: include it as an amenity and charge more. But AC isn't really needed in our area except for a couple days out of the year. That's one of the major hesitations to buy AC units.

Looking for some ideas!