Engine cooling fan ISX

[Big red 09]

Hello been awhile and a great forum
I have same truck and it is 2009 T660 Isx 525/1850 motor
Having what I would consider a unique cooling dan problem I run local haul so routine is same every day as far as truck travels When I leave home in the morning after normal truck warm up and get about ten miles on the engine fan tries to come on but does not engage fully and belt is trying to slip as it’s doing this. The engine temps are not demanding the fan be on. When it tries to turn fan on the light is not coming on the dash either. I can also turn on the manual switch and then the fan will turn on fully as normal including the dash indicator showing it’s on. As soon as I shut off the switch the fan will stop momentarily and then try to do a partial engagement again. Here’s the baffling part. After this starts approximately ten miles into morning start it will do this partial fan engagement process for approximately 20 minutes and then it will completely go back to normal or proper running (as needed for normal operating). When I turn on the manual switch I do this to stop the belt from squeaking and to see if would help stop it from happening but it does not change problem
I have changed the solenoid that controls the fan located on firewall but to no avail. This problem occurs every morning of last several days and is almost right to the T as to the timing. Fan is acting like the air supply is is being lost partially (to start engagement process) I have checked air leaks on lines and at connections and see/hear no leaks and with that being said this problem on happens initially in morning and once it returns to normal it will not do again until the next morning
Looking for some ideas as what to check. Could the solenoid do a partial on/off due to a voltage that is not enough or ecm doing something? I guess the biggest mystery is the partial engagement of clutch and the fact that it only happens in morning
Thank you for any support of this weird problem!