The load fuses for aux fans are under a panel, behind the fuse box. This is the relay box and has 6 screws to be removed for access..
Once there , the fuses are on top of each relay.. one for high fan [ engine coolant] and one for low fan [ a/c ]
These will be slots B and C.
The high fan has been upgraded by Benz to a 25 [ from 15]
The low fan is a 30 [ low fan requires more amps b/c of the dropping resistor in that circuit]
There is also a fuse in the fuse box for the primary side of the relays , but that is usually not the culprit , as low relay current is nil...
Do the test TK recomends and that will verify if fuses need checking...