Cummins isx fan stay on

Is your air pressure low? Typically they will run on high gear if you have low air pressure. Also if your A/C is running while your idling they tend to stay on for a long period of time. Thats just the way ISX has it programmed. Ive seen it on every model that has an ISX motor.

 

There is a switch on the front end of the engine that is air actuated. If it fails fan stays on

 

This could be your fan clutch worn out or, as stated, your A/C is turning it on. Sometimes the A/C pressure switches fail or the wiring shorts and causes the fan to run continuously or intermittently.

 

I replaced mine, thinking that it was wore out because it wobbles just a little bit. Turns out it's suppose to do that. $440 from the Pete shop. There's a air line off the fire wall above the engine that you could pull off and put some air to it. The fan clutch will pop back and forth if its OK. That's all I learned about it so far.
Hope this helps.

 

Mine was in NYC.
I can't figure labor as I had other things done with the clutch.