Tru-cool trans cooler 40k. Help

[whammy91]

I bought the trans cooler from circle D. I've read that this is the trans cooler to get. So I got it. Mounted it in front by the lower grill that way it gets good air. Now I've notice my trans gets hotter when it should stay cooler. I drove it for about 1hr and it got up to 250 degrees. I have a trans temp guage. Before I did the trans cooler maybe the highest it ever went up was like 220. But this trans cooler make it climb faster. It has been kinda hot here lately but I still find that odd. Also when I installed it. I left 1 line open and pump trans fluid in the other end of the cooler till it flows out the other end that way the cooler alone is full of trans fluid. Any help with the people that are also running this trans cooler.