The refrigerator compressor does not consistently turn on when supposed to. Twice in past month has remained off long enough to spoil food. When I manually reset it by turning the thermostat to off and back to desired temperature, it returns to working properly. However, when on vacation, this is obviously not possible (such as last week). I recently cleaned the coils after the first time it stopped a month ago. In reading another thread, I wonder if it is a problem with the defrost timer. How do I confirm this, or might it be a different problem? Thanks!