I have a fridge with a bottom freezer that the defrost water channel ices up every week or two . The evaporator lies flat in the partition between the fridge and freezer .

I remove the floor of the fridge section and defrost the area around the fan motor and blade to free up the blade and melt the ice blocking the hole for the water to drain out and it works OK for approximately a week or two , and then the same thing happens .

I`ve checked the drain system at the back (drain hose , trap etc) and NOTHING is ever plugged . When I defrost the ice with a hair dryer , the defrost water flows freely down to the pan every time .

The defrost components all work OK because the fridge is going into a defrost cycle and the evaporator coils are clear after a defrost cycle

A repairman told me that this was not an uncommon problem for this type of fridge , but he didn`t have a solution for the problem .

The fridge is just over 10 years old (I think) and this problem has just started recently .

Any help would be GREATLY appreciated ........