A very valid point....They are heat resistant, because in servers where there is heavy processor load generating heat as high as 70 degrees, these fans blow out the air to make the CPU cool. Also, they are being protected by the radiator fan itself, which is also running to cool down the radiator and condensor as well.
About weather and water, yes, they are prone to water to some extent. But you can protect them against water by:
1- postioning the fans on condensor in such a way that the side from which wires originate is heading toward ground.
2- While servicing the car, avoid splashing the High pressure water stream directly to the face of condensor. Water that is poured on to radiator from above does not affect the fan.
3- When its raining, of course turning on the A/C should be avoided at all costs. Plus, driving the car in pool of water could damage the fans.
In short, the fans could only be affected when its heavily raining. I will certainly ask about the protection mechanism in this case.