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Have you ever opened your fridge and noticed that your milk carton looks a little sweaty? Or your tea isn’t particularly iced or your brand new yogurt is halfway to cheese when you open it? If that sounds vaguely familiar, your fridge may not be working as well as it should be. Refrigerators have a gasket—a long rubber piece—that helps keep cold air in and warm air out, but if the seal isn’t working properly, it’s not doing its job and the stuff in your fridge is probably warmer than it should be.

Before you call for repair assistance, there’s one quick way to test if your fridge is sealing properly and it just requires a dollar bill.

First, open the door and look at the seal. If you see a gap area that’s worn through, or a spot where the seal has come loose, your gasket probably needs to be replaced. Even if the seal looks okay, your work isn’t quite done yet: Grab a dollar bill out of your wallet, open your refrigerator door and close it on the dollar bill, leaving a piece sticking out. If you can pull the bill out easily, it may be time to replace the gasket.

WATCH: How To Clean and Organize Your Fridge

Try the dollar bill trick on a few different spots on your fridge to test the seal around the door. If you can pull the bill out in any spot, you can either try to push the seal back into place and test again with a dollar bill. If pushing the seal back works, and you can’t pull the dollar bill out, you’re good. If you can’t get the bill to stick, you may need to replace the gasket. Also, if the bill comes out sticky or gunky, the gasket may not be sealing as well as it could be.

After your careful assessment, you can either call the repairman and pass along that information, or you can try to repair the gasket yourself.  Most home centers or appliance repair shops sell gasket replacement kits. However you get your gasket fixed, your milk should be safe from sweating soon enough.

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