Open the freezer door on your side-by-side refrigerator. Empty the bottom two shelves of the freezer to gain access to the drain plug.
Remove the screws holding the plastic panel in the back wall of the freezer covering the drain plug. Lift off the plastic panel to expose the drain plug bottom floor of your freezer.
Thaw the ice buildup inside the drain line using hot tap water and a turkey baster to force hot water through the drain. Continue to force hot water through the drain until you can hear water running through the drain and into the pan below it.
Mix together 1 tsp. of baking soda with 2 cups of hot tap water. Flush the drain line with the turkey baster to clean it.
Wipe any excess water from the floor of your freezer with paper towels and replace the plastic panel. Return the foods to your freezer, and shut the freezer door.