If a refrigerator is starting from room temperature and is frost free, it takes four to six hours to cool to the correct temperature. However, it takes the refrigerator about 24 hours to stabilize with a normal on and off routine to keep the refrigerator cool.
The refrigerator must be installed where the temperature will remain between 60 to 110 degrees Fahrenheit, or it won't cool properly. Refrigerators take so long to cool down because they have to get rid of the heat from the plastic, insulation and metal from inside. The freezer cools down first, followed by the fresh food sections.