Does anybody know how to force my fan clutch "on" to check to see if it is working properly? I can feel some resistance when I spin the fan by hand after the engine sits overnight, and when I warm up the engine, then shut it off and immediately spin the fan again it feels pretty much the same. I can't really tell much difference between fan resistance at hot and cold engine temps. I can not detect any leaks around the fan clutch assembly - but I have not removed it so I can't get the best look at it. I have tried to just start the truck and let the engine idle until it gets hot enought to engage the clutch, but it never seems to kick into high gear. I know what the roar sound of a fan coming on sounds like but I have never heard my truck's fan do that. It also has never overheated - so when it sits and idles it never overheats but I can not hear the fan engage either. I am not sure whether it is working fine or not. The only reason I suspect it may be bad is because my A/C seems to not work very well when sitting still. At what point do these fans kick into gear? Truck is an 02 Z71 1500 with 91k miles. Do those clutches "wear out"? Any insight anybody could give would be greatly appreciated. THanks!