There's clearly a short somewhere. It's either the fan speed resistors (in
the fan switch) or the fan motor is jammed with debris, or the motor is
shorted out (rare but it happens).

You need to identify the power connection to the fan motor. You might be
able to get at this under the dash or by removing the glove compartment
door, or perhaps the center console items. If the fuse blows when the motor
is disconnected, its something else.

Figure out how to pull the fan switch panel out and look for burned
resistors or contacts. If the fuse blows when the switch is disconnected,
its something else.

You may need the schematic at this stage. The heater and air conditioner fan
fuse may be controlling the a/c clutch and condensor fan relay too. Try
disconnecting these items too.