series 60 clutch fan

That sounds like the Kysor type that is locked until you apply air.

First, put regulated shop air directly to the fan, 90 to 100 lbs and see if it disengages. See if you hear any leaking.

Next, build up air pressure and shut the engine off. Take the line that comes out of the solenoid that activates the fan and turn the key on. You should feel air coming out of that line. If you do not have air coming from the solenoid, put your own 12 volts to it and see if it lets air come through.

I don't know about other make trucks but freightliner trucks have their own control unit that is a Kysor unit that controls the fan clutch. They are known to go bad.

Whatever truck that you have you need to Google the fan clutch circuit and see how yours is your setup.

If the fan clutch itself is bad, you can buy a kit from kitmasters. I think the kit for the fan clutch and the bearings for the pulley is about $200 or less. They also have excellent customer service that will help you if you have any problems.

 

Why don't you post a picture of your fan and the number for ordering a kit.

Hopefully somebody should be able to give you a better idea of what's going on.
I never heard of a kit that costs that much, but anything is possible

My kit was less than $200 including the bearings.

What year and make is the truck? Did you test that the clutch fan itself is bad?

 

Don’t know what year Truck you have. Freightliner started using these EDM’s around 2000. It combines control of 4 different sensors, one of which is the fan. I forget the details, but info on it is on the forum somewhere. It’s located in the bottom of fuse panel. I’m not saying it’s your problem, but something to consider.