I came across a great guide to test what is wrong with your fridge. The URL is http://www.gasrefrigeration.net/dom_techdata/MAN_SM.PDF
This guides teaches you how to test if you need a new heating or cooling unit. I discovered that both of my fridges had blockage, one of each kind. This requires a new cooling unit. After checking the price ($450) I decided to buy a new fridge.