I have a frigidaire side. I have a frigidaire side by side refrigerator. Recently water started

Question

I have a frigidaire side by side refrigerator. Recently water started collecting at the bottom of the freezer unit and eventually seeps out the bottom of the door. All other operations of the unit seem to be working normally. There is no obvious water leak so I suspect a problem with the evaporator during defrost cycles. Is this likely and how can I diagonose it for sure? Thx