[mreid]

Important safety tip: Shut off power before removing/installing electrical components!

The problem as you are finding is that a short can cause all sorts of problems. At best the affected component stops working completely. I recommend to ring out (check continuity) of your fan circuit. It sounds lke a ground problem where you are getting stray current backfeeding through one fan. You also should double check your replacement job. There's a good chance you mis-wired it.