Fan Clutch Confused

[mekelly]

I just replaced my cracked fan and fan clutch. In reading the forum, the fan is supposed to spin when the car is first started and then disengage if cold air is flowing over the radiator into the clutch.

The fan always appears engaged. I guess it's possible it's disengaging when I am driving but if I drive the vehicle for 2-3 minutes (before the thermostat opens), stop, and open the hood, it's always spinning. never seen it not spinning.

I am sure the clutch is good as it's brand new, but would love to see the engine running and the fan not spinning if it's not required. Any other ways to demonstrate this?

 

[Anime]

Just because a fan clutch is new doesn't mean it works perfectly.

Also, even a fan clutch that does work perfectly never actually fully disengages - it still spins the fan, just with much less engagement and less load on the engine.

One of the best ways to check is by sound - if the fan is always roaringly loud, like an airplane taking off, the fan clutch may be seized in the fully engaged position and not letting up.

You can also check with the engine off and spin the fan clutch, if it has a lot of resistance and doesn't spin at least a little freely, you might try taking it back to whereever you bought it and exhange for another one.

Also keep in mind there are three different "types" of fan clutches that have different ranges of engagement. A "severe duty" fan clutch is engaged pretty well even at it's lowest level of engagement, a "heavy duty" is not engaged as much when cold but engages good enough when hot for towing and other such use, and the "standard duty" fan clutch is lightly engaged when cold and only a medium amount when hot, so it's really only designed for vehicles with a manual transmission that don't need extra cooling for towing or hot climates.

So, if you stick a severe duty fan clutch on there, it's going to be engaged a lot more than a heavy duty fan clutch, same if you stick a heavy duty fan clutch on there if the stock clutch was a standard duty.

New fan clutches also take time to break in, so a new clutch won't always disengage as much when new as it will after it gets some mileage on it.