2007 379 fan runs all the time

[hct5]

2007 379 the fan runs none stop once up to temp, the coolant temp is around 200-210 all the time even empty running down the highway with the A/C off. all the parameters in insite look good. coolant has been flushed and filled with new and the radiator has been blown out. oil temp sits around 220. pulled the thermostate and everything looks good there as well and is the updated part. Any thouths of what to check next? it has a cummins 870.