Just put a new GM Clutch in, comes on when you start it up and runs for a while, then goes off so I think it is operating right. Got overheating the first time I towed since replacing the fan clutch, 87 degree day and pulled a steep hill, overheated to about 230-240 and the fan never cut on. I guess it could be the cooling stack needs to be cleaned but did that 60k miles ago... must be clogged again... not sure why it is clogging up so often.
Just put in a new fan clutch but it will not engage on a hot day pulling a trailer and pulling a steep grade. It seems to engage on start up as normal but is not working while towing pulling a hill.