Do you have a refrigerator that has a frost buildup in the ceiling of the freezer? Maybe the packages of food in your freezer are covered in a coating of frost. Well if you have a frost buildup in the freezer ceiling or on the walls or packages of food, the first place you would want to check is your refrigerator door gasket. If the freezer gasket is defective it will have to be replaced. When I say defective, I mean ripped or torn significantly where it is not sealing properly. If the gasket is not making contact with the refrigerator and it is not torn, ripped or damaged, it most likely does not need replaced. It is possible that your refrigerator door has flexed or is bowed.
Usually when a freezer gasket is defective it is torn in one spot. When only one spot on the gasket is torn the warm humid air from the room get sucked in at that exact spot and you will see the frost / ice buildup at that point. If everything is frosted over, and there is frost on the freezer ceiling, the gasket is usually not defective in just one spot.
If you have a frost build up on the ceiling of the freezer and your freezer gasket is not damaged and is sealing properly then most likely the problem is that someone did not close the freezer door completely. Sometimes when the fresh food door (not the freezer) is closed quickly the freezer door will pop open.
This is completely normal as long as the freezer door closes itself. How does a freezer door pop open? Closing the fresh food door forces a massive amount of air into the fresh food section. And since the fresh food section is connected to the freezer through an air channel, the air quickly rushes into the freezer a smaller space, and causes the freezer door to pop open or actually burp. Most refrigerators today have a one way air valve to release this air without the freezer door opening, but your valve could have failed.
If you have a frost build up on the ceiling of your freezer, the gasket is not defective, and the door is not bowed or flexed then you probably had a package of food on the shelf or door preventing the door from closing.
And finally all the above advice assumes that you do not have a defrost problem. In other words no frost buildup on the evaporator due to a defective defrost system component, such as the defrost heater or defrost thermostat.