If the heater checks out ok and the defrost thermostat works it is the timer. You can turn the timer till it clicks and check to see if the heater comes on. If it does the timer isn't running. Part 257 on this diagram. http://www.searspartsdirect.com/partsdirect/getSubComp.pd?diagramPageId=00007&documentId=00053650&modelNumber=3639512585&productCategoryId=0165000&brandId=0582&modelName=&backToLink=Return+to+part+list

Woodchukie,

When I did finally opened the panel the lower section of the coils were frozen. The upper section was not. They did defrost during the troubleshooting process. My question or doubt is what will be a real reading on each of the heater resistances, they look like a spring inside a glass tube. Presently the coils are frosted, but I still don't get enough cold air to the fridge. Even thou I have not installed the freezer back panel, just in case, it is not easy. I did turn some the defrost control knob, it only turns one way, but I am clueless on how to check it, I could not find an electrical diagram on the unit. Thanks for the hints. Hector

As mentioned in denman's post, the fan has to be running to distribute the cold air.

If that is an uneven frost pattern on the coils then that is a sign of low freon in the system, requireing a tech.

When you turn the defrost timer, you should feel or hear a click which is either turning the heater on or off. Watch the heater. It will glow red when it's on. During the troubleshooting you said it melted the ice. Did all of it melt and you now have the normal light frosting or did it not melt all of the ice.