This is the temperature I was dealing with today when I tested it out.
I put 2 bags of ice in the chest and then added another after a half hour. Had to drive to Stanley's location so that's why the time gap. I left the ice in the bags. Turned the fan on while I was warming up Stanley (he's in a garage). The cooler was in the back seat. I took a 20 minute 6 mile jaunt. Half the time the sun was in my face and the other half the sun was behind me. I kept the windows up. There was a small difference and I didn't die in that 20 minutes but was still hot but not as hot as it could've been. I would've liked there to have been more air flow. While the fan isn't bad I think I need more of a hurricane. After 3 hours I took the ice out of the cooler. Probably an inch worth melted so I think crushed ice will last longer than an hour and a half like one of the videos I saw said. I don't have a lot of experience with coolers so that's why I want to test everything. In the bag, out of the bag, crushed and big block. Out of the bag would most likely be best. Makes sense to me anyway. Not sure why some folks in the vids I've seen left it in the bag. Anyway, we are now looking into a larger fan. I'm also thinking two fans. I believe the PVC is plenty big enough so that's not an issue as far as I'm concerned. Just need more air pressure. The experiment continues.