I can't tell... Ive contacted customer service twice and they won't tell me. I did find a document somewhere that showed a line running diagonal up the sides, but I can't find it!
I'll have to take a look tonight. They did tell me it contains a sealed system tubing and not to drill, but I think they are taking a stance on ruining their product. They claim there are no diagrams as it's not a replaceable part.
I just felt the side, it's cold in the basement so the sides of the fridge are pretty cool. There is a warm spot on it as well, couldn't tell if there was a direction that it ran though.