If there is any electrical connection between the supercharger and the fan circuit, it is an opportunity for a denied warranty claim for anything that fails on that circuit. I might add that there is still the question of why the fuse failed in the first place. As well, while I do perform mods on my vehicle, I am also fully aware that I may be required to expertly refute a dealership's claim of said mods being the source of part or equipment failure. In addition, labor charges are determined by a guide book and may or may not reflect actual time necessary to accomplish any given task. Further, the things that you claim you were being "charged" for are on the estimate. You weren't actually charged for anything other than an hour of labor for a diagnosis that you dispute. Finally, have you followed the contact instructions
provided on Ford's website for unresolved issues with dealerships? The problems that people have with dealerships of ALL
brands and makes are legend. While it is distressing that you have had this experience, it is not unique to Ford as a corporation, this could happen at a Chevy, Toyota or Mercedes dealership. Ultimately, the onus is on the owner of a modified car to follow the chain of contact and expertly refute the claims of a service manager. Unfortunately, this is a responsibility that comes with the act of performing mods on your car.