I have a jenn air Jfc2070krw French door refrigerator. The freezer is cold refrigerator warm and the vertical strip on the left door is warm. Ice build up in the freezer - already been taken apart and defrosted. How can I know what caused the problem and what part may need to be replaced? Now that the ice build up is gone the refrigerator is getting cold but I'd like to figure out what caused the problem. Thanks!