If I purchase a single family house with an illegal apartment will it affect the banks mortgage decision?

I am interested in purchasing a single family house on Long Island, NY which currently has an illegal apartment upstairs with a kitchen with a stove, sink and refrigerator. When the appraiser comes to look at it and notes the upstairs kitchen, will this affect the bank's decision on whether or not to give us the mortgage loan? If so, is it possible that we can just disconnect the stove and somehow cover up the sink when the appraiser comes? What about the fridge? is that also illegal? Please help!!