I have been running them for about 2 years. There is a controller for each fan and it is very easy to adjust each one individually. The harness also can be spliced in to your AC clutch power wire so that when the AC is on the fan is constantly running. I am very satisfied with them. If you call and talk to them they will spec out a pair of fans specifically for your needs. I live in Mi so it doesn't nearly as hot as some of the southern states but I have no issues with the truck getting too hot even pulling a several thousand pounds. I haven't had a chance to test them with a real heavy load yet.