Please check the following:
1. Whether the refrigerator is placed in direct sunlight.
2. Whether the refrigerator door is closed.
3. Whether the refrigerator door is opened frequently within a short period.
4. Whether there is too much food inside the refrigerator.
5. Whether uncooled food has been placed in the refrigerator.
6. Whether sufficient space has been left around the refrigerator (recommended clearances: 30 cm above, 10 cm behind, 5 cm on each side).