2011 pathfinder fan issue
 

I just recently replaced my thermostat in my pathfinder, now that I replaced it, my fan is working overtime and is always on. My temperature gauge at first wasn't going up and down and staying high but now it's in the center like usual. I do have coolant in there just worried its going to over heat on long drives. Any help would be great. I'm not very mechanically inclined but I'm willing to try anything from you experts.