Ways to keep the back of a pickup truck cool

Suppose I want to keep the back of a pickup truck (covered by a cap) at a comfortable temperature when the truck is parked somewhere in a warm climate. This could be for the comfort of a person sleeping while traveling or a dog temporarily confined there. What are some steps that can be taken to do this while spending as little money as possible?

The easiest way is to park in the shade.

You can also get an inflatable gasket that fits between the truck vent window, and the vent window at the front of the cap. While you’re driving, you open the two windows, and allow the A/C to blow in there.

attach a pair of truck nuts to the hitch and drop the tailgate, you’ll be redneck cool in no time.

now, seriously, maybe buy some cheap clip on battery fans and some dry ice?

I wouldn’t go with dry ice. While I doubt that the CO2 would displace enough oxygen to suffocate someone, it never hurts to play it safe.

Personally, I’d never put someone or a dog in a sealed area like that in the South in summer. It just gets too hot. Could you get a cap with vented side windows, and/or open the tailgate window?

I assume that leaving the rear of the bed cover open isn’t an option, maybe with some kind of screen/security mesh?

Other than that I was thinking a couple of solar-powered fans would do the trick. They sell things like that for keeping cars cool when you leave them parked on a hot day - maybe get two, one blowing outside air in and the other removing hot air from the interior.

i figure the fans would evacuate the CO2. one fan drawing in, one fan venting out.

These are called “Arctic Air Coolers”. They’re a type of portable airconditioner favored by some of my pilot buddies. There are a lot of reviews, and if you search a little*, you can find lots of homemade versions and plans on the net. Anecdotal reports say they’re good for 3-4 hours, but keep in mind that pilots typically climb to cooler altitudes for part of their flights. This probably prolongs the cooling time of these units. I suspect one of these would work nicely for keeping a truck bed cool for a few hours.

In the past, when I’ve traveled with my dogs, I used a truck cap with large window openiings on the sides (with screens). Leaving plenty of water seemed to keep my dogs happy, without any special equipment. My truck and camper shell were both white, though.

*I’m at work, with limited search capabilities, or I’d post more links.

Thanks, thats a cool idea and looks like it would be fun to make. Found a quick description here: http://www.instructables.com/id/Portable-12V-Air-Conditioner---Cheap-and-easy!/step1/Background-and-How-it-Works/