Stupid question about A/C

[PureChevy]

There is a switch on the dash mounted under the steering wheel. Almost where you would think someone would mount a fog light switch or something. When i first bought the truck i thought it was an old light switch that someone had dissconnected cause there werent any fog lights. Well i was under the hood the other day and noticed a small electric fan. I didnt pay much attention to it but it is hooked to the switch and runs. the fan is attached to something that looks like a tranny cooler. I dont think my truck would have a tranny cooler so it must be part of the a/c. Right?
looks almost like a small radiator. I am sorry, i dont have any pictures.

the best i could figure was that it was used to help the a/c cool off on a real hot day.

any ideas???