If the blower fan isn’t working correctly, or at all, step one is to replace the final stage resistor. This is cheap, easy, and the cause of most blower motor related issues in E46/E39/E53/E38s.

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2011 M3
2006 Sierra 2500HD 4WD LBZ/Allison
2004 X5 3.0i 6MT
1995 M3 S50B32
1990 325is
1989 M3 S54B32

Hers:
1989 325iX
1996 911 Turbo