My Subzero 650 (36" bottom freezer) works great and keeps refrigerator compartment at a steady 34 F. But ice forms on the bottom rear behind the vegetable crisper and it gets so thick that the drawer won't close all the way. If it gets much worse, I'm afraid the fridge door won't close. Below are two pix -- one with ice, and the other after melting the ice with a hair dryer. Am I just keeping the fridge too cold?