If the fuse is not blown the most likely fault is the final stage unit or the fan motor.
Bmw e46 auxiliary fan relay location.
This relay location requires that the glovebox be removed for access.
If the fan runs erratically continuously with the key removed from the ignition or not at all and the fuse is good the speed controller has.
Fuse box diagram location and assignment of electrical fuses and relays for bmw 3 series e46 316i 318i 318d 320i 320d 323i 325i 328i 330i 330d.
There is no engine driven mechanical fan.
The bentley repair manual shows the location on page ecl 20.
On all bmw models up through the late 90s the auxiliary or main fan is controlled by one or two thermostatic switches that are mounted into the radiator side or bottom tanks.
For the bmw 3 e46 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 model year.
This is the electrical fuse and relay box under the plastic cover in the passenger side rear of the engine bay.
There s a clutched fan spins off the water pump belt driven behind the radiator standing in front of the car facing it and there is also an electric one in front of the radiator.
Various relays in the bmw e46 the first set of relays is located behind the glovebox.
While troubleshooting the e46 aux fan is outside the scope of this document i ll point out that the e46 design replaced the individual relays with a speed controller integrated with the fan.
To me it sounds like you re talking about the electric auxilary fan.
The fan is mounted between the radiator and the engine and is the main engine cooling fan.
Bmw e46 electric fan fix and troubleshooting testing fan signal on dme https youtu be rdibbrn3 30.