I mean maybe the aux pump rather than the blower motor is drawing the amps to blow the fuse. Unplugging it is a simple test.

Does the 116 have a ventilated resistor box for blower speed control? Maybe there’s a short in one of the resistors. Blower starts on high then fuse blows at lower speed.

Sixto
98 E320s sedan and wagon
02 C320 wagon