Originally Posted by Arthur Dalton

OK

That [ D] is low fan load circuit.
Couple of easy test
1 . turn each fan by hand to see that they are both free.
2 .Check connections on each side of resistor, they burn and make a bad connection
3 . Take a jumper wire with an amp meter wired in series and jump from Bat+ to the terminal with 2 wires on it at resistor. This is fan draw and should not excced 25 A.. if it does , you have a bad fan motor .. if fine , Benz has upped fuse D to 25 A on double fan models.
Lastly, there has been wire problems between the relay and resistor for low fan , so check any for burnt at the relay end too..