snow inside of fridge
You should look to see if air flow vents around the bottom of the refrigerator are clogged up with dirt and dust bunnies. If so clean that up with a vacuum cleaner. It may be well to remove the unit from the cabinet to clean out the whole area.

Also this problem can be brought on by failure of the air circulation fan in the refrigerator.

Some questions remain:


Is this installation new and you are just experiencing this problem?
In the past has there been successful use of the refrigerator in its current configuration all through a year or more of ambient temperature cycles?
Is this a refrigerator without a freezer compartment?