I noticed this afternoon that the temperatures on the refrigerator and freezer are both - and when I hit the up or down nothing happens. The food in the freezer is defrosting. What is wrong?

First check the basics.Inspect both freezer and fridge door.Are both getting properly closed.Or any of the door is not getting completely closed.----------- But if both doors are getting properly closed, then this problem relates to faulty/ weak compressor.---------

The compressor is weak.The compressor needs to be replaced.-------------- The working procedure of your refrigerator unit is as follows: --- The compressor starts then it cools the freezer section. When the freezer reaches its cooling level the defrost cycle starts functioning. In this cycle the fan in the freezer section starts running and the cool air in the freezer section is passed to the fridge section and the fridge section gets cold. The air from freezer to refrigerator passes from the section, in that section the damper is located.------------ But as you mentioned that food freezer is defrosting, this indicates that freezer not cooling properly,this indicates problem with compressor.When compressor cools the freezer section then fridge section gets cold.If freezer section is not getting properly cold then fridge section will not cool properly/.So the problem relates to compressor.---------- In the compressor there is a refrigerant called FREON.With the help of this Freon the compressor cools the freezer section.Freon is a gaseous type cooling agent.The compressor will stop cooling when coolant gets leaked from its chamber.--------- Again recharging the Freon is possible, but the cost for that recharging is approx the cost of new compressor.So its always advisable to get compressor replaced.Because new compressor has warranty for few years.------------------ You can get required parts from from online sites like: --- www.repairclinic.com or from searspartsdirect online site. --------- -----------

But before going for compressor replacing.Try this reset procedure and see, if that helps:---

The manual defrost reset procedure is as follows : ----
First unplug the unit from main power outlet. Then empty whole unit completely. Then keep both the doors open. Wait for 24 hours. All the ice collected on the coils and in the freezer section will get melted. Clean the water from the sections. Then Connect the power cord of the unit to main power outlet after 24 hours/.Then set the temperature to normal in both fridge and freezer section. Then check, it will take approx 4 hours to regain/ run its cooling cycle.If you still get same problem, then its compressor problem.It has to be replaced.-----------

This should help.Thanks.Helpmech.