, this top mount refrigerator was intermittently not keeping items in the fresh food section cold enough, and was freezing everything in the freezer section hard as a rock. Because everything seemed fine one day, but the next day the milk was sour, the customer thought it was time to get this refrigerator fixed.
Refrigerators with the freezer section on top (top mount) usually mount the evaporator portion of the refrigeration sealed system behind the rear panel and circulate air with the aid of a fan motor. These fans will blow cooled air through an air inlet into the fresh food section of the unit. As the cool air falls, it absorbs heat from the food items until it becomes warmer than the contents of the cavity. The warmer air begins to rise and re-enters the freezer section through one or more air returns. The warmer moist air is drawn through the cool fins of the evaporator by the fan motor where the heat is absorbed by the sealed system to be released outside unit.
Because of the complaint of a very cold freezer, and a warmer than usual fresh food section, I knew the sealed system components were most likely operating fine but due to the intermittent nature of the complaint, I needed to check the entire system for operation. I started with removing the rear cover to get a look at the evaporator and fan motor. Everything was operating as expected, so next I turned the temperature control to a higher setting to see if the unit would cycle off which it did indicating it was working correctly. But when I turned the temperature control to a lower setting to turn everything back on, the fan motor didn't start as expected. Instead the fan blades rotated at a painfully slow rate and not nearly fast enough to move any air. A quick flick with my finger brought the fan up to normal operating RPM, so it looks like I found the problem.
As the unit turned on and off with the temperature control, the fan would not spin up to speed, but when the door was closed, the vibration was just enough to get the fan running again. That is why sometimes it seemed to cool properly, and other times it didn't. I installed a new evaporator
into the freezer section (just a few screws) and now the unit keeps everything properly cooled.