Hi I have a kenmore elite that was manufactured in 4/2000. I was seeing frost build up on the back of the freezer wall. I was told that I needed to replace the defrost timer also at the same time to replace the thermastatic control. Which my tech did. I still have frost on back freezer wall so I was instructed to replace the freezer control assembly. Which I have done. I still have frost forming on the back of the freezer wall. When this happens my items in the freezer are thawing the temp. in the freezer is reading at 10 to 20 above 0. At the same time the refrigerator temp. is 45-55 and my food spoils quickly. If I turn the unit off and take a hair dryer to the freezer to melt everything than turn unit back on it seems to cycle through the defrost cycle but within 24 hours it starts to form frost on the back wall in the freezer and then warm up in the refrigerator . Any ideas what is wrong