We didn't know if ours worked either when we bought it. We ended up testing it out while bringing it home, with restaurant leftovers overnight in a fairly warm part of California. At that time, I wasn't even 100% certain the van had two batteries/electrical systems, so it felt a little risky.
I was surprised by how quiet it was, and though it doesn't get "super cold," I'd heard it was "just a cooler" so didn't think it would get very cool at all. It was plenty cold for the task at hand, and ran all night without problem.
It's not "instantly cold" though.
Have you tested it by, say, putting a bottle of ambient-temperature water in it and leaving it on for a while? Maybe a second bottle in the open part of the van, and compare the temperatures of each after a few hours?