Sometimes refrigerators are warm at the top. If this is the case, your cat may be enjoying the warm and cozy location.
Cats also jump on the refrigerator because cats like to be up high. There are a couple reasons why your cat likes to be up high. For starters, when cats fight, the cat that is higher is usually the dominant one, while the other cat is the submissive one. Secondly, cats like to be high so they are safe from predators. Another possibility is that your cat wants a fresh view of the environment!
Cats instincts tell them that they are safe and secure when they are up high. This is the same reason why cats climb trees when they are outside.
Have you ever seen a firefighter rescue a cat from a tree? Cats sometimes climb up high on objects and then do not have the ability to get back down.
Hopefully your cat knows how to get down off of your refrigerator.