Fan always comes on. Even at 170!!!

[04onrockstars]

So lately my truck has been a pain. I blew two little holes in the radiator so we replaced that. The coolant tank had a crack and we replaced that and the lid. The fuel filter was leaking and we had to fix the gasket. And since all these problems started and since we have fixed them my running fan will not turn off. It comes on when im driving down the road and it never turned on unless i was pulling the bobcat on hot summer days. Any ideas? The scangauge says the temp is always right at 170-180. Its the big really loud fan that normally turns on around 220??