Ziggy52, we noticed a significant difference in the interior temp when we turned the vents on the CoolCat so that they directed the air up in the trailer. Turning on the Fantastic Fan also seemed to help circulate the cold air. Otherwise it seemed to pool in the lower part of the trailer. Before we tried this, the lower three feet (or so) of the trailer was cold and, as we straightened up, we stood up into heat. It was kind of weird, like diving into Lake Superior, warm on the surface but frigid below! Also, we use the two bunk arrangement on our A213HW and discovered that our bedding was hanging over the side of the bunk and blocking the air flow from the CoolCat from getting up and out.
I know this is pretty simple stuff but it worked for us.