Why does the radiator fan run even when the cars not started
If it's coming on even when the engine is cool you most likely have a relay issue to the fan or a control issue to the relay.
Check your temp sensor to see if it's working correctly
The fan on that vehicle is digitaly controlled by the vehicles DME if the fan is running all the time even with the vehicle off then te fan module (fan assembly itself) is faulty
Looking for a Used 3 Series in your area?
CarGurus has 30,181 nationwide 3 Series listings starting at $900.
Search BMW 3 Series Questions
BMW 3 Series Experts
Related Models For Sale
Used Cars For Sale