The fridge gets its cold air from the freezer through a vent between the freezer and fridge. There is a flap you adjust with the fridge temp. control. Make sure it's open.
If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air and eventually affect the freezer too.
check defrost timer, defrost heater, defrost thermostat Refrigerator Repair Guide: How To Fix a Refrigerator - ACME HOW TO.com
You can go ahead and defrost manually if you remove the back panel and melt it with a hair dryer. That way you don't have to remove all the food. It will ice back up in a week or so but that will give you time to check it out.
In most of the new units they now have the adaptive defrost control. It senses when to defrost based on how many times and for how long the door is opened. It's more energy efficient but there does seem to be lots of problems with the board.
Need your model number to know which you have. | 
Refridgerator 7 Freezer 
