The DEFROST DRAIN is plugged!!! If you remove the rear wall INSIDE of the freezer you will find The evaporator coil. Under the coil is a drain tray, I think you will find it FULL of ICE!!! If you MELT the ice out of the tray,you will find a 1/2" hole in the tray, what you need to do is: Melt ALL the ICE!!! Even under the metal tray!!!! There will be a hole under the tray that water goes through and runs into the pan under the unit. Take a TURKEY BASTER and fill it with HOT water and FORCE it down the hole until water runs freely down the hole!!! Put it back together,YOUR DONE!!!:)