I use a 12 volt swamp cooler all the time in my Jeepster. It's a portable thing, about the size of a small ice chest. I lash it down behind the front seat, or set it on the floor of the right seat if nobody's riding shotgun.
Works great when the weather's dry and 115 degrees. Not as good as refrigeration, but very effective, and the engine doesn't need to run, windows don't even have to be closed. I can let it run while away from the vehicle for awhile, then when I get back it's nice and cool inside.
Fill it a little too full and it starts spraying a fine mist out too, really nice.
I move it from the Jeepster to the motorhome, depending on where I need it.
A friend had it for years, gave it to me.
I don't know who makes them, never seen one like it.
I've been thinking that would make a good little side business for me, making them.
I think I could turn them out for about $80, if there was much of a demand.
98% is Understanding it
Just throwing parts at it doesn't solve anything.