I had that happen once and what it was is that one blade of the plug in slipped to the side of the connector and did not make contact. I just unpluged it and pluged it back in making sure both blades on the plug made contact. Hope that makes sense. usally when that happens you may find some of your outlets in the rig dont work. like the person above stated each side is 30 amps.
I took a large truck windsheild shade with the silver thick type from wallys and cut it to the shape and the wife sewed the edges afterwards to make sure they stayed together and then I just wedge them in or tape them in when needed.
Hope that helps or gives you an idea on how to block out the heat.