You should check the seal on your refrigerator every so often. You can do this by closing the door on a dollar bill. If you can pull the bill out easily, it's time to replace the gaskets. You can buy these replacement kits from either an appliance dealer or a home repair center.
I learned from an appliance repair man that to keep your refrigertor seals from cracking and have them last a very long time you should periodically coat them with a very thin layer of vasaline after cleaning. I took his advise. Not only is it keeping the seals in good shape it is also keeping the doors closed solidly against the refrigerator. Especially important in summer weather..