How can I stop ice build up in my Samsung Cool n Cool?

I have a frost free cool n cool which keeps building up with ice at the bottom of the freezer. Each mobth I need to chip out th eice so that the drawer will open and close. There appears to be water slowly dripping out of the air vent at the back of the freezer. It drips descretly out of the freezer and has wreked our floor. Does anyone have a sollution?