It's probably not the exact one you're looking for, but the ARP Fridge Defend works well: https://www.arprv.com/products.php#4-arp-3.1-2-fan
Wiring setup is a lot more involved than the basic PC fan, but it doesn't require getting on the roof and it'll also prevent damage if the fridge is run off-level. I got the version with one exterior fan and two interior fans for my Bigfoot
. The exterior fan made it work well in hot weather instead of falling behind above 94F ambient, and the interior fans keep the temperature a lot more uniform.