Typically, a refrigerator should start cooling down within a few hours after being plugged in. However, it may take up to 24 hours for the refrigerator to reach its optimal temperature. During this time, it's normal for the freezer to cool down faster than the refrigerator section.
If you've just purchased a secondhand refrigerator, there are a few factors to consider if the fridge section appears to be warming up instead:
Temperature settings: Ensure that the temperature settings are correctly adjusted. The recommended temperature for the refrigerator is usually around 37-40 degrees Fahrenheit (3-4 degrees Celsius). Make sure the temperature control is set appropriately.
Door seal: Check the door seal or gasket to ensure it is properly sealing the refrigerator compartment. A faulty seal can allow warm air to enter the fridge, causing it to warm up. Make sure the door is closing tightly and there are no obstructions preventing a proper seal.
Air circulation: Verify that there is sufficient airflow inside the refrigerator. Avoid overloading it with too many items, as this can obstruct proper air circulation and affect cooling performance. Leave some space between items for air to flow.
If you've checked these factors and the fridge section is still not cooling down after 24 hours, it may indicate a problem with the refrigerator that requires professional inspection or repair. In such cases, contacting a technician or the manufacturer's customer service for assistance is recommended.