[d77n]

I've been collecting water under the refrigerator bins and from reading these forums I've believe I have a clogged defrost drain tube. After removing the back wall of the (top freezer - not side by side) freezer compartment, I can not see where the drain is. I think there is just a pan with a drain hole in the middle under the coils. From there it appears it goes into the fridge behind a temperature control panel at the top of the fridge section and then out the back of the fridge directly behind this panel. How do I unclog this line and from where?