Final Stage Unit / Blower Resistor, Aftermarket - E60, E63

Blower fan problems in your BMW E60 5 series (2004-2010) including E60 M5 and E63 6-series  (2004-2010) including E63 M6 are likely caused by a faulty blower motor resistor, also known as a blower regulator, final stage resistor (FSR) or final stage unit (FSU). It regulates the fan speed coming from the blower motor. If your blower motor seems to have a mind of its own the blower resistor is the first part to check or replace. A failed FSU will cause the fan to not work at all, only work on one speed, or alternate the fan speed on its own. It may even cause battery drain as the blower runs even with the car turned off. Since the FSU is tricky to access, most people simply replace it rather than test it. 

The majority of FSU failures are caused by old age and excessive heat and a fresh FSU should remedy your problems. However, note that the FSU may be the victim from a related component failing elsewhere in the system. Inspect the plug housing and pins on the wiring harness for signs of excessive heat. When replacing your FSU, also consider changing the microfilter and inspecting the blower motor operation (a failing blower motor may be a contributor to premature FSU failure).

This part is manufactured by an aftermarket supplier of European auto parts, including many electrical components. While not carrying OEM status, this part follows the design of the original very closely and uses similar materials. An aftermarket part may even have the same TUV approval as its OEM counterpart. The brand may even be OEM to another manufacturer besides BMW. This aftermarket brand has a two year warranty - the same as Genuine BMW and OEM brands.