take the freezer wall off again, this time check this part, its the defrost thermostat, it can cause the problem, Also check the defrost heater,The defrost timer is located in the control panel where the thermostat is located , Did you find those parts
I do not not know where to look for the thermostat (PN# XXXXX) or how to go about replacing the heater (PN# XXXXX) if that is bad. These part numbers were obtained from: http://www.searspartsdirect.com/partsdirect/getSubComp.pd?diagramPageId=00006&documentId=M0209143&modelNumber=59672222200&productCategoryId=0161000&brandId=0582&modelName=&backToLink=Return+to+part+list
Hope this aids you in assisting me with my efforts!
Great the timer is ok, if the defrost heater did not come on, then look at the defrost thermostat, point to the freezer coil you will find the location of the defrost thermostat.
Replace the defrost thermostat