I have a Kenmore Model 106.73854302 not sure how old it is, at least 5 years old (came with the house). Recently I defrosted the freezer to clear an ice dam in the drain tube for the defrost cycle. the freezer has operated just fine for about 2 weeks, now it only cools to just above 34 degrees. The freezer fan is functioning properly. Any ideas of what to check or look for?