Fan not coming on. 09 International Transtar 8600

Hello Everyone , I am new to this forum and far from being a mechanic. Any help would be greatly appreciated. I have a 2009 International transtar 8600 with a Maxxforce 11. My fan is not coming on when the engine starts getting hot. When I first turn on the truck the fan comes on, and I can hear it more as I accelerate but will turn off when I get up to speed or after a few minutes. I doubt it is my fan clutch. The engine doesn't overheat when idling or running. It's just when I'm pulling a heavy load or warm weather the trucks water temperature will get up to 200 degrees and the fan won't come on. My guess, is that it might be a fan solenoid. Or something that regulates or tells the fan to come on at a certain temperature. When I do the regen, the engine will get too hot for me to complete it because the fan doesn't come on and I have to stop it. Thanks in advance

 

Thanks. The temp gets way past 215 without the fan engaging. I will check it out

 

Thank you. The truck isn't equipped with a fan switch override. And I am actually considering putting one on If all else fails. Like you mentioned, it might be best to get ahead of the heat

 

Thanks for your reply. Sounds like a promising fix, and just what I was looking for. But like I mentioned, I'm far from a mechanic. Could u please be a little more specific of the location of this sensor, I have no clue what a water rail is. Sorry. I'm just a new owner operators trying to make it thru this Pandemic. Thanks again

 

Thank you. Yeah the fan does run at startup up and works fine. The only time I get a check engine light is when the temperature reaches 215 which I assumes is because the fan doesn't kick in at that point. So should I check the solenoid first then ECM?