Cold air needs room to move, and a wall of groceries blocks that from happening. AndreyPopov via Getty Images Opening the refrigerator door too often in a short timespan can cause problems. “A lot of people set their fridges either too warm or too cold,” Palmer-Spring said. Mistake #6: Neglecting the door sealThat rubber gasket running around the door keeps cold air in and outside air out. With cold air escaping, he said, the fridge “will run longer and more frequently,” forced to overwork to make up the difference.