I block all but a 2x2 inch square in the summer. I also run the ac which in turn runs the fan on low, so it hovers around 186 degrees all summer long.
When its below 85 degrees out I run a full block year round. Best I can say is get s sg2 or some odb2 reader to watch your water temp and test it.
When this frozen stuff is over Im going to remake a lower air dam out of edging or gutter down spout like I had last year.
