Close a dollar bill in the door.

You can tell by feeling for cold air leaks and using the dollar bill test.

The simplest check: close the lid or door on a dollar bill (or a piece of paper). If you can pull it out with almost no resistance, the gasket isn’t sealing. Do this in a few spots around the perimeter.

If you see visible cracks, warping, or mold, that’s another sign. Also check for condensation on the outside near the seal—means cold air is escaping. Or just put your hand around the gasket and feel for a draft. If it feels noticeably cooler near the edge, replace it.

A bad gasket makes your compressor work harder and your ice melt faster. Not worth ignoring.