Its fuse 23 in the PDC which is the fuse box under the hood of the vehicle. There are two relays for the fans. A Low and a High speed relay but they both run off the same fuse and i would think they would be labled on the cover to the fuse box. And yes snow build up in the fans can cause the fuse to blow. Ive had several cases on Jepp liberty's from them blowing fuses for the radiator cooling fans in the winter. The dealership you took it to can say its not under warrenty and it may not actullly be i dont know for sure, but they wouldnt have a way to prove it was snow unless it was packed full when you took it to them. It would just be a possibility.