A refrigerator door gasket must make continuous contact to hold cold air inside. A dirty corner, a twisted seal, or a door that has sagged can create a small leak that increases frost and run time. A simple paper test and careful cleaning often reveal the cause.
Look for the pattern
Inspect the gasket all the way around with the door open. Look for splits, flattened corners, food residue, or sections pulled out of their channel. Check whether the cabinet is level and whether shelves or bins prevent the door from closing fully.
Perform a paper test
Place a strip of paper between the gasket and cabinet at several points, close the door, and gently pull. Some resistance should be present around the full perimeter. A paper strip that slides out easily at one location identifies an area for closer inspection rather than proving the entire gasket is bad.
Clean and reshape
Wipe the gasket with warm water and mild dish soap, then dry it. Warm, not hot, air from a hair dryer held at a safe distance can help a lightly deformed corner relax; never overheat the plastic or leave the appliance unattended. Press the seal back into its channel if it has shifted.
Know when to replace it
Replace a gasket that is cracked, brittle, or still leaking after cleaning and alignment. Use the appliance model to order the correct part. If the door is visibly sagging, the hinges are loose, or the refrigerator runs continuously, address that underlying condition before assuming the seal is the only problem.