Detroit 60 Eng Fan Clutch not engaging

Sounds like a selinoid problem. If I recall correctly, it has an electrical connection, Maybe a wire is broken somewhere. Or the plug itself is loose. Check the wire near heat sources, and also in an area where it has movement. Freightliner probably sells a new pigtail for it. With a foot or 2 wire. Just an idea. I fixed my low coolant sensor that way. It worked intermittently occasionally for a few years, till I figured if out. There was a bulliton on my 99, the fan came on all the time. Till I changed the selinoid. Upgrade included a new harness with instructions for spicing it in. Needed a special crimping tool, loaned by the dealer, luckily to do the job.Now my 01 has the same problem. I think it’s caused by the power distribution module, in fuse box. I don’t think yours has one. If it does, it will be found at the bottom in fuse panel. Small 4-6” box marked pdm. It replaces 3 or 4 sensors, temp, fan, and a couple others. I’m not saying these things are your problem, just my own experience with fan problems.

 

I see yours is an International, I doubt the bulliton or the pdm box will apply, my mistake.

 

I have a Volvo 2001 with 12.7 Detroit and had a similar issue. I replaced the solenoid and also replaced the air lines to the solenoid and to the fan clutch and problem solved. You could also be experiencing a problem with the APAD module intermittent malfunction that sits under the cowl above the washer fluid reservoir. It usually will flash the green light slowly when working properly. Also check the AC high pressure switch located on drivers side of radiator and charge air cooler. If it is faulty it will send the bad signal to the ECM as well.