I was going to say almost the exact same thing as
@sachilles. Gondolas RARELY have to have people rescued from them. There is almost always a way to move the cables enough to get people off of them. You can bet Disney will have the most redundancy possible to ensure this never has to happen. I think a failure once every 5 years is more accurate than 5-10 times a year. (Don't get me wrong, it will STOP often as people do stupid things getting on and off, but then it will restart within a minute or two.)
As far as the AC debate - I don't know how they would be able to NOT have AC in the Florida sun. Those Gondolas will be like small easy-bake ovens. It may not be a strong system, but it will be something that keeps the Gondolas from being 110 degrees.