Don't leave hot water running while doing dishes. Check the seal on your refrigerator to make sure it's not allowing cool air to escape. Close the refrigerator door on a dollar bill. If it slips or slides out easily, the gasket may need to be replaced. If you have a second refrigerator that holds only a few items, consider whether you really need it.
Many people keep a second refrigerator in their garage.
On a hot day when the temperature in your garage is over 90 degrees, the unit will struggle to keep the temperature inside of the refrigerator at about 40 degrees.