GE Freezer fine; fridge cools only when freezer door open
I have a GE refrigerator with top mount freezer with which I have had consistent problems since I purchased it 7 years ago (computer board had to be replaced after only 3 years; the part through with the cold air flows into the fridge started freezing with ice build up about 8 months ago stopping airflow into the fridge requiring me to manually defrost the refrigerator twice,etc.)
The latest problems are 1) water build up in fridge (which I understand from the forum is probably due to blockage of the defrost hose) and 2) I discovered the fridge was 60 degrees F yesterday and, after investigaing, discovered cold air flows into the fridge only when the freezer door is open (if I leave the freezer door open and depress the freezer door latch to simulate door closure, the air keeps flowing into the fridge; but if I close the freezer door, airflow into the fridge ceases). There was heavy ice build up in the back of the freezer compartment but only a small amount of ice on the exterior back of the airflow tunnel in the fridge (no ice inside the tunnel).
I emptied and unplugged the appliance and am currently letting it thaw. Once thawed I will clean the coils and unblock the defrost tubing if it is clogged but I think there is a bigger problem here. Could someone respond to tell me where to look (e.g. evaporator motor, condensor, compressor, etc.) to diagnose and repair the problem.
Also, can someone tell me what the two square holes lined with styrofoam at the bacl left and right of the refrigerator compartment are and what the implications are if they fill with ice?