Sounds like your drain tube down to the tray at the bottom of the fridge is blocked, so when the freezer defrosts the water ends up in the fridge.
Since you are getting water in the fridge, the drain probably comes from the freezer and drains into a funnel like part at the back top of the fridge, then down a drain tube, out the back of the fridge and down to the tray
The tubing can usually be cleared by using a turkey baster and forcing water through it. Also is a good idea to force a 20% bleach solution through it once cleared. Mold etc. likes to grow in the tube
Cold also be a cracked /leaking funnel assy. |