You should unplug your refrigerator if away for 4 months or longer.
While some food may be okay in the fridge for 4 months most food will expire by then regardless and there's the potential for a power outage which could cause food spoilage.
If the food spoils in the fridge it can make the fridge smell really bad when you return.
Removing all the food and unplugging the fridge will also save electricity and you will return to a clean fridge.
Wipe down the inside of the fridge with a rag and prop the door open to allow ventilation.
If you are going away for a month or longer, it is always a good idea to unplug your refrigerator to save on your electric bill.
Empty your refrigerator, drain the water tank if you have one, clean the inside of the refrigerator and leave the doors open to avoid any unwanted odors.
A freezer can be left plugged in and should if you have frozen foods as frozen foods can last longer and the electricity saved in that instance is not worth the loss in food.
I always unplug my refrigerator after emptying it and leaving for longer than a month but I leave my deep freezer plugged in.