Decreasing the fridge temperature opens the vents more and increases air circulation from the freezer. The temperature can be adjusted using the controls found inside the refrigerator or freezer. The ideal freezer temperature is about 0 to 5 degrees (F) and about 38 degrees (F) for the fridge.Measure the temperature by placing a cup of water with a cooking thermometer into the refrigerator for about 2 hours or more.To test the freezer, substitute alcohol or cooking oil.n most refrigerator freezers, the refrigerator gets its cold from the freezer. The evaporator fan circulates air over the coils in the freezer and cold air circulates into the refrigerator through vents.