I've had one of these since it wasn't cool (pun intended). I'm only 30 but made several trips about 10 years ago across Texas, Arkansas, Tennessee and into Missouri in a 1950 Dodge Meadowbrook which was ALL stock but rebuilt. 230" 6 cylinder, Fluid-Drive transmission, 6v electrics, etc.
I used an under-dash heater from a 1950 Ford truck (a period accessory, it didn't say Ford like others I've seen), its built-in fan (which was already 6v, same as the car), some coil type duct hose from its defrost outlet to the back seat area (passed under the front seat), an old 60s style metal cooler in the back floorboard, and a 12v water pump from harbor freight. The pump was run on 6v which slowed it down and actually made the cooler work better I think. It was heaven for those summer road trips. It all blended in perfectly, just looked like an era-correct heater (the car had its own under the hood) and an era-correct cooler. The hoses from heater to cooler were run together through a factory hole (removed a metal plug) in the rear floorboard, inside some old fire hose for protection, under the floorboards and connected to the heater core on the engine-side of the firewall. I wasn't concerned about the inefficiency of the blower because it only ran when the car was running, this was a travel vehicle, not a camper.
The cooling ability of the system lies in its ability to remove heat from air and transfer it to the liquid being pumped through the heater core, and use that heat to melt ice, cooling the liquid. This is important. Ice basically replaces the compressor and condenser of an AC system. The more ice it can melt, the better it's cooling. A block of ice would be good for lasting a long time but the slower it melts, the less cooling you'll have. I just had a big cooler in the trunk for drinks and stuff and bought 2 bags of ice at most gas stops (1 into the cooler inside, 1 into the trunk cooler for reserve). This thing could really go through the ice on hot days but it made the drive more than just bearable, it was very comfortable. I kept the metal cooler as full of ice as possible (If I forgot the air temp would rise, letting you know the ice was gone) and let the water drain from the cooler (added a stand-pipe to its stock drain), and out the hole in the floor, as we drove. I'd added a sump to the metal cooler (cut up a plastic milk jug with the pump's suction line inside) so it kept JUST ENOUGH water in the loop to keep all the hoses and the core full, thus the pump couldn't run dry but I wasn't wasting any cooling power on keeping excess water cold. There's always more water available as the ice melts. In retrospect I'd've been better off having 2 compartments inside a big cooler: 1 with just ice with a water drain, and 1 with the ice and water I was currently using. It would've lasted longer this way and still given maximum cooling for the ice volume on hand. The only problem I ever had with the system's original design was the condensate dripping and being blown from the heater core in the southern humidity. Drilled a hole and ran a lil copper tube back out the firewall. It looked just like the car had AC with all that condensate dripping from the passenger side firewall.
This system could freeze if I added a little salt to the ice so I know it was cooling as much as possible with water (as opposed to antifreeze) and the breeze coming off the core was VERY refreshing on long summer drives. I bet that junk is still in the attic of my dad's shop...
