Where is the defrost timer and control located GE tfx30pr?

I have a GE TFX30PR side by side refrigerator and have been breaking the ice build up on the bottom of the freezer for a while, thinking the hose is plugged. I've checked it and it is not and now believe that it is likely the defrost timer or controller. It is not located in the front behind the grill at the bottom and I don't know where to look. Help please.