The coils were icing and not defrosting

Un Plug the refrigerator. Remove the lower shelves and shelf brackets on the freezer side of my side-by-side refrigerator. Removed the 5 screws on the lower back cover plate and removed the cover. The thermostat is on the top of the coils, it snaps around the coil, carefully slide it off. Cut the two wires to the thermostat near the end. splice the new thermostat to the wires in the refrigerator using wire nuts or wire clamps, either wire can got to either connection, snap the thermostat on the top of the coils, replace the cover, replace the shelve brackets and shelves, plug it in.