We have both wall (high) mounted and low (portable) fans in our studio. The clients that like to have low fans (in their face to to speak) will ride near those bikes.
I once subbed for a class that had a hard-core "anti-fan" cadre and one of them was quite vocal about his distaste for fans (to the point of trying to belittle those who wanted them--in a "soft" manner)--but one client requested fans. So, I turned a few of them on.
The client (Mr. anti-fan) got up and LEFT THE CLASS. He then (of course) complained to the GFM and the club owner. When asked why I chose to ignore the wishes of one and grant the wishes of the other I simply stated that I think they'd rather have to deal with a somewhat miffed client than to explain to a doctor/family/court of law why you chose to ignore the reasonable request of a client who subsequently suffered heat injury--(fill in the rest of the story).
Our official policy is if ONE client wants a fan--we turn them on in stages to accomodate them. To deny their request is opening your club and you personally (in some regions) to liability issues.
When participants understand this--they usually nod their heads and get on with the business at hand. Riding strong!
-Cheers