3406E 1LW fan settings

I have 3406E 1LW19521. Just finished platinum in frame at KW at 980k due to coolant in oil.
I told KW to change fan setting that in ecm from 217 down to 205. But they saying there was no fan setting when they tried. I know tbey were using USB Link 2 and Cat ET 2020A. So is this something i have to go to the Cat and have them change fan settings or is it impossible to change it. Im not looking for flash file for right now, just lower fan settings like 205 on and 195 off
Thanks

 

I installed 180f thermostats long time ago before in frame. And when they did in frame i paid extra for 2 new cat 180 thermostats. Truck runs 179-181 all day long cruising on flat. On hard hills i use manual switch to cool it down. I just want lower ECM settings for precaution

 

So only way to get 205f fan on and 195f off is to get pre low nox file ???

 

Well it have to be hooked to the ECM because AC, i think AC uses ECM to turn fan on when idling and when i get up to speed it turn fan off and fan never comes on for AC when im driving only at traffic lights and idling. So maybe i can install thermo switch that will give pover to truck manual switch that i have on dashboard ??? This way it womt back feed ECM