If you have no fans w/ac on, Your first test should be that jumper test.

Most Fail that test and wind up just being the aux fan fuse..mostly b/c Benz had a habit of under-rated fuses on that circuit and the fan motor gets old and draws a little more current than when new..
If you do have such a condition [ w/blown fuse ] , also spin the fan motor by hand to make sure it is nice a free..they get full of crap and that drag blows the fuse.
You will find it..........
And if the fan/s do work with a/c on as they are supposed to, and the engine still o-heats with no a/c on, then the diagnosis goes right back to Duxs original..

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A Dalton