What Is a Swamp Cooler in Automobiles?

Window-mounted swamp cooler
Window-mounted swamp coolers were popular before the widespread adoption of air conditioning.

Phil Parker/Flickr (Creative Commons 2.0)

Nearly every car that rolls off the line these days comes equipped with air conditioning, but that wasn’t always the case. The technology didn’t show up as an OEM option until 1940, and nearly three decades slipped away after that before more than half of new cars offered an air conditioning system. Even then, many people considered air conditioning to be an expensive luxury.

So, what did people do to keep cool on hot, summer road trips? Rolling down the windows was always an option, but those in dry climates often leaned on a device commonly known as a swamp cooler.

What Is a Swamp Cooler?

Swamp coolers were decidedly low-tech, low-cost devices that many dealers offered as optional equipment. The most iconic design was a window-mounted tube that could often be paint-matched to a new car and decked out in chrome trim. These devices bore a passing resemblance to miniature jet engines, and vintage units are sometimes even sought out to complete the look of a newly restored classic car.

How Do Swamp Coolers Work?

Unlike air conditioners, which rely on the vaporization and condensation of a liquid refrigerant, swamp coolers operate on the principle of evaporative cooling. When water evaporates, it pulls heat from the surrounding air, which has a cooling effect. Evaporative cooling typically requires less energy than vapor-compression air conditioning, and many swamp cooler designs have no need for any electricity.

Since swamp coolers rely on the evaporation of water to cool off the air, they don’t work very well in humid environments. They work best in areas where the air is very dry, in which case they can also improve the quality of the air by adding water vapor.

One common swamp cooler design used a carpet-like substance that was mounted along the inner diameter of the cylinder. That material could then be rotated through a water reservoir. Whenever the car was in motion, air would be forced into the cylinder, pass over the wet material, and then enter the vehicle. Due to the effect of evaporative cooling, this would lower the overall temperature inside the passenger compartment.

Does Anyone Still Make Swamp Coolers?

In addition to the iconic window-mounted car swamp coolers, some companies offered dash-mounted units. Some of these units were capable of accommodating ice, in addition to water, which could increase the cooling effect.

While there don’t appear to be any sources of new or OEM window-mounted units, there are a few companies out there that still manufacture dash-mounted swamp coolers. These units are bulky, so they’re not really sized for most modern vehicles.

Can I Make My Own Swamp Cooler?

Since swamp coolers are so low-tech, it’s pretty easy to just build your own. You’ll need a few basic materials, including:

  • Five-gallon bucket or ice chest
  • Drill with a hole saw bits
  • 12-volt van
  • Mounting hardware
  • Ice

The basic idea is to mount the fan to the bucket or ice chest. You’ll need to drill an intake hole for the fan to blow into and some outlet holes for the cooled air to pass through. This will provide you with an air conditioning alternative that you can use in your car, home, office, or anywhere else.

If you use a bucket, you may find that frozen water bottles will last longer than regular ice. However, using regular ice in an ice chest will allow your DIY swamp cooler to still perform its original function. It might not have the same retro-cool look as a vintage unit, but no window-mounted swamp cooler ever kept anyone’s drinks cool on a long road trip.