this seems like such a basic question, i'm embarrassed to even ask...
the can clutch, does that mean the fan can "free wheel" when the clutch is not engaged? my fan always spins, always engaged and spins in relation to engine speed.

 

To a degree it free spins it will always spin but when the clutch engages it will be 1:1 or close with rpm. It with the engine of you should be able to spin it with some resistance and when you shut the truck off it shouldn't keep spinning for a long time.

 

well it seems like my fan is always matched with rpm, never makes more or less noise, and if i rev the engine cold from under the hood it speeds right up with the engine.

 

If you have a stock fan it will run all the time but slowly. When it does engage it sounds sort of like the roar of a jet engine. An easy way to check is to get a couple sheets of newspaper and cover the radiator completely. Go out for a ride and watch your temperature gauge closely ( it will take a while at least for my truck ) for the truck to start overheating. I had to go about 8 miles if I remember right before the gauge moved off of its normal position. It about another mile before the fan actually started to work. I pull off the side of the road and remove the papers by the time I got back in the truck it had pulled back down to running temperature. If you readies little flat between the radiator and the front of the grill you can slide the newspapers in their they should stick out enough to fold them over the flat. It uses for a winter front FYI, rain does not cause the paper to stick to the radiator were called and the other problems. Just my two cents, Mike.