2008 peterbilt 388 engine fan

I have a peterbilt 388 with a cat c15 accert. Here recently I noticed the engine fan running constantly so after some research I found the Ac high pressure switch are known to go bad so changed it and the fan turns off now. Now the problem is the fan stays off until the engine temp reaches 190 and kicks on for about 2 minutes and cools the motor down just under 190 then turns off for about 10 seconds then kicks back on when the engine temp gets back to 190. This happens over and over all day. It gets real annoying. Any ideas what my problem could be? Thanks in advance.

 

Turning the ac off has no effect on it. And the manual override switch has never worked since we have owned the truck.