Well actually the AC condenser, but gives the same effect of less air for cooling. We found on our last trip that the add on cooling fan in front of the radiator helped quite a bit in keeping the 6.0 Chevy cooler, both water and transmission, so I decided to add a second fan in hopes of getting even better.
After pulling the lights, grill, existing fan and trans cooler, I found a very interesting pattern of crud on the AC compressor. Some areas are pretty much completely blocked.
The pattern of the crud follows the opening in the plastic "floor in front of the condenser, with more on the passenger side that has the bigger opening for the transmission cooler lines. The bumper cover at the front of the van has a couple of inches of clearance under it, open to under the van, and that lines up with crud along the bottom of the condenser. It certainly looks like MUCH more dirt and stuff is coming up from under the front of the van to the radiator, than is coming straight in the grill. It is currently at about only 25K miles, and not a whole lot of gravel roads and such, so it looks pretty unusual, especially with the rest of the condenser pretty clean.
What might be at least part of the problem is that the front wheelwells are pretty open into the grill and radiator area.
You can even see the tires from the radiator area. I am starting to think that roadspray and dirt are getting thrown into that area, and the sucked into the radiator, by the front tires, especially if the road is wet a bit.
This certainly could contribute to the heat issues the Chevies have, if other vans are doing the same thing.
I think I will make some plastic wheelwell liners/baffles to see if it helps, but I need to be careful not to reduce airflow to the radiator in the process.