Never heard it called "swamp cooler", but we had one for our 37 Chevy when I was a kid. It was mounted on the passenger side window, and you occasionally poured water in it. Air rushing in was directed into the car...I seem to remember it didn't help much..........still, we bought one (just called a 'water cooler') for the house soon after. A hose was attached to the intake at top and adjusted to a slow drip thru the 'excelsior' (shredded wood) batting as a squirrel-cage fan blew the slightly cooled air into the house. If you were very hot and stood in front of it, you felt better than NOT being in front of it. I remember once going with my father to a distributor for a new batting to replace the rotting one.

We finally got a real AC after several years.