sworkscooper

I am not too familiar with the F set up . I believe it is similar to the MPI Mini in that if the engine ECU does not see a viable signal from the sensor it will turn the fan on as a safety feature. It could be a poor connection to or from the ECU or as you say just a case of the switch being faulty. Forum members who own an F will be able to guide you better than myself.
John .