No air-conditioning in Central America?

I am planning a family trip with my parents to Costa Rica and just about every one of my questions has already been answered... The only thing I'm finding is when I'm looking for house rentals and such, in any place, none of them have air-conditioning. Not even the really expensive rentals that we won't be staying at anyways. All the websites say something like, "The breeze comes in through the entire house and the fans on the ceilings keep the air moving." Well... I personally have no problem with this, but I know my mom may be more concerned because she's never traveled outside of U.S./Canada and Europe. So I'm wondering how "cool" these houses really stay, since the average day temp in Costa Rica is always in the 80F range. So, who's stayed in non-air conditioned houses in warm climates? I've stayed like this in Peru, but that country is more cold than warm.
First-responder: Dude, I know... I need my mom to go though. I'm planning all this and I'm not even going to let her know there's no air-conditioning. It's a surprise. But I mean, I don't want her sweating to near-death. That's all I'm saying.

That's why I never leave the house without my personal homeostatic enviroment hazard suit

Those type of places are a bit like East coast USA type, hot and humid (depends on the area). But bring a small personal fan and stuff.