Model #AFD2535DEW, this bottom mount refrigerator was cooling properly in the freezer section, but the fresh food section was noticeably warm. This temperature rise was confirmed by the sour milk discovered by the customer the next morning. No amount of adjustment seemed to make a difference, and after throwing away most of the items in the fresh food section, it was time to get this unit cooling again.
Most refrigerators use a sealed system of refrigerant to provide for the cooling of the inner cavities. The cooling generally takes place in the freezer section through the use of an evaporator coil which the refrigerant flows through with the aid of a fan motor. Air is drawn across the evaporator which removes the heat leaving cold air to continue to flow on to the fresh food section of the unit. The air enters through a refrigerator part called a damper or diffuser which controls the amount of cooling in the fresh food section. The cold air being denser will fall to the bottom of the cavity absorbing heat along the way. It is then returned to the freezer section where the heat is removed by the evaporator and the cycle continues.
When looking at cooling problems on refrigerators, it is always best to examine the unit and isolate the failure depending on the symptoms and your own observations. Total failures where there is no cooling at all are much different than a partial failure of one part of the unit. A total failure could indicate something as simple as a thermostat failure to a more serious sealed system failure. Partial cooling, however, we at least know the refrigeration system is working, so our search can conclude we are more likely looking for an airflow issue than something more mysterious.
Because of the partial cooling, and a well cooled freezer section, my checks began with the airflow system. Since the freezer is on the bottom of this unit, movement of cold air to the upper fresh food section is very dependant on the flow of air by the evaporator fan motor. Any disruption in this motors operation or blockage of the air is very likely to make things start to get warm up above. This is a common problem when the defrost system stops working resulting in the evaporator looking like a block of ice and preventing good airflow. But a visual inspection of the back of the freezer section gave no indication of an ice buildup, so I proceeded to see if maybe the air was being blocked somewhere else.
Usually a quick way to check for good airflow is to put your hand up near the air outlet which will be located somewhere near the top of the fresh food section. If the fan is running, but you don’t feel any cold air, either the evaporator coils are blocked, or the damper isn’t open. This unit has a simple grill cover over the damper and air outlet and once removed, it was plain as day that the damper door was closed. Opening the door by hand provided a rush of cool air which further indicated everything else was working fine.
Dampers can fail to operate for various reasons depending on the make and model of the refrigerator. Some are simple mechanical devices, while other use motors to open and close the passageways. So when dealing with motorized models, we must always ensure we isolate the problem to either the damper, or the board that is controlling the damper. This can be done by checking for voltage to the motor from the board. Since it is warm in the fresh food section, the board should be trying to open the damper. Check for voltage to the motor. If you find voltage and the motor isn’t working, the damper has failed. If you don’t find voltage, then it is more likely the control board has failed. Some further investigation would then need to be made as to why the board is cooling but not allowing air to flow.
On this refrigerator, it was a simple voltage check at the connector to find voltage present, but the motor was not working. After unplugging the refrigerator for safety, I removed the old damper, and installed the new damper into the mount. With everything put back in place, and power reapplied, the compressor and fans came to life, and after a brief moment, the damper opened as expected. The customer was instructed to give the fresh food section an hour to two to get back down to an appropriate temperature before adding food and she was happy that there would be cold milk for breakfast.