I have a subzero 650 which works great except in the summer during high humidity. I get iced up coils... icing is behind the aluminum back panel, around the evaporator coils (NOT down under the crisper drawers) I have to pull out a heat gun and defrost 3 times a summer. A pain. Is there any way to increase the frequency of the defrost cycle? any other way to get around this issue? Local subzero person will Not work on the machine because I got it from a secondary source. Love this frig EXCEPT for this giant throwback pain in the butt problem. thanks