Diagnosis
The doors are out of alignment, which breaks the magnetic seal (gasket) at the center mullion. This lets warm, moist air in, causing the fridge to work harder and frost to build up.
How to Fix It
You can adjust the doors. You’ll need a helper. 1) Open both doors. Look at the top hinge cover where the doors meet the cabinet. There are usually plastic caps you can pop off to reveal the hinge screws. 2) Loosen (but don’t remove) the screws on the top hinge of the door that’s misaligned. 3) Have your helper hold the door in the correct position—it should be flush with the cabinet and the other door across the top and down the middle. 4) While they hold it, tighten the hinge screws back down. 5) Check the seal by closing the doors on a dollar bill. It should be held firmly when you pull it. Repeat the adjustment on the bottom hinge if needed.
If That Didn't Work
If the doors are aligned but the seal is still bad, the gaskets themselves might be dirty or damaged. Clean them thoroughly with warm, soapy water and dry them. Check for any tears or permanent kinks. If they’re damaged, they’ll need to be replaced—you can order the part, but installing new gaskets is a finicky job that takes patience.
Heads Up
Don’t over-tighten the hinge screws, as you can strip the holes in the cabinet frame. Just get them snug. And make adjustments in small increments; a quarter-turn can make a big difference.