idr

The temperature in my kitchen is about 22 centigrade, in my refrigerator about 4 C. Sometimes I open the refrigerator and take somethng out, then close it and after some seconds I open it again. And then I must apply much more force to open the refrigerator door. It means that opening the door for the first time lowered considerably the pressure in the fridge compartment. Why is it so? As I understand, when I open the door for the first time the hotter air from the room enters the fridge compartment and the pressure should rise and not fall. Please explain somebody Thanks