If your refrigerator door isn’t sealing like it used to, you might notice frost building up in the freezer or your milk turning sour a little faster than normal. That’s because the rubber gasket that lines the door is what keeps the cold air in and the warm air out. Over time, this gasket can crack, warp, or simply lose its magnetic grip, and when that happens your fridge works harder, uses more electricity, and struggles to keep your food at a safe temperature. The good news is that replacing a door gasket is one of the most satisfying and budget-friendly DIY repairs you can tackle. You don’t need to be a professional appliance technician to get it done in an afternoon.

Before you start, take a close look at the current gasket. Run your hand along the seal and feel for any soft spots, tears, or areas where the rubber has pulled away from the door. A quick test is to close the door on a dollar bill and try to slide it out. If it comes out easily, you’ve got a leak. Once you’ve confirmed the gasket needs replacing, the first step is to find the right replacement part. Look for the model number on a sticker inside the fridge, usually on the wall near the top or on the side. Write that down, then search online for a gasket that matches your exact model. You can also call an appliance parts store with your model number. The gasket might cost anywhere from thirty to eighty dollars, which is a whole lot cheaper than a service call.

Now for the actual swap. First, unplug the refrigerator and empty the door shelves, or at least clear the ones closest to the gasket so you have room to work. Some gaskets are held in place with screws behind a plastic trim piece, while others simply pull out of a channel. If you see screws, remove them with a Phillips screwdriver and take off the trim. If the gasket is the pull-out type, grab one corner firmly and give it a steady tug. It might feel resistant, but it will slide out. Don’t yank it too hard, though, because you don’t want to warp the underlying channel.

Once the old gasket is off, clean the channel and the area around the door with warm soapy water. This is also a great time to wipe away any crumbs, sticky spots, or mold that might have been hiding under the old seal. Dry everything completely. Now take the new gasket and let it warm up to room temperature if it’s been sitting in a cold box. This makes it more flexible and easier to work with. Starting at the top corner of the door, press the new gasket into the channel, working your way around the edges. If it’s the screw-in type, line up the holes and reattach the trim panel, then tighten the screws gently, not too tight or you’ll pinch the rubber.

For pull-out gaskets, you might need to use a little patience. Some models have a rope-like core inside the gasket that helps it sit snugly. Push one edge into the groove, then work your way around, using your thumb to seat it fully. A butter knife can help you push stubborn sections into place, just be careful not to cut the rubber. Once the gasket is all the way around, close the door and check the seal. You should hear a solid click when the magnetic strip meets the fridge body. If you notice any gaps, especially at the corners, gently pull the gasket out and reseat it. Sometimes a heat gun or hair dryer on low heat can soften the rubber enough to make it conform better, but don’t hold it in one spot too long.

Finally, plug the fridge back in and give it about an hour to reach its normal temperature. Check that the door opens and closes smoothly and that the seal looks even all the way around. One last dollar bill test is a good way to confirm your work. Properly sealed, the bill should be difficult to pull out at any point. Not only have you saved yourself the cost of a repair technician, but you’ve also extended the life of your appliance and improved its efficiency. Your fridge will hum along happily, keeping your groceries cold and your energy bill lower. And next time you see that little rubber seal, you’ll know exactly what it does and how to fix it when it wears out.