Joe,
There may be a small amount of mechanical air movement, but it seems that convection is at work as well. The air moves at a wisper out of the open grate on the top of the unit parallel to the hinged side of the top loading door. The side and back open grates don't have much air flow over them. However, I think the way this works and one reason for the low current draw is that the large open grates expose the condenser coils which then slowly moves heated air up and out of the unit via the top open grate. I looked in my unit to see if I could locate a fan--- it might be there, but if it is, its pretty low volume. There is no "fan" sound that I can hear over the already quiet operation of the compressor motor (which has only one moving part).
So however it works, there isn't much air volume movement, but I think it still needs some open area around the mechanical side with the grates to allow air movement to carry heat up and away from the coils.
One other neat thing, you can quickly remove it from the travel lock and take it on trips (camping anyone?), stowing it in the back of the van (or SUV). The travel lock adds about an inch and a half to the overall height of the installation, and I highly recommend for a rolling sailboat!
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