I'm sure you have all noticed this. First thing in the mornings on a cold day, the first 50 yards you drive in your truck it sounds like the cooling fan is running Hyper-Speed or something. It never lasts beyond 25mph or so, but it seems like when I leave the neighborhood, that fan is pulling LOTS of air!

Is this because the clutch hasn't warmed up enough to work properly, or is this some of feature designed into the PCM? I figured since the fan has a thermostatically controlled viscous clutch, it needs a proper "warm up" to release the first time.

I thought about temporarily disabling the cluck somehow to make my fan run without the clutch feature. Of course this would cause lots of drag and therefor decrease gas mileage, but I just can kill the curiosity!

Does anyone have a diagram of how these fan clutches work or what's inside them?

 

I figured since the fan has a thermostatically controlled viscous clutch, it needs a proper "warm up" to release the first time.

 

Guess I kinda answered my own question then, huh?

 

I would say yes.

I will also say that you don't want the fan to run all the time by disabling the clutch(not sure how you would do that anyway).

My clutch ceased up and ran constanty it robbed me a power and MPG (about2MPG). Not to mention that horribly loud noise is constant including being as loud as my TSL at 50 on the highway. A continuous running mechanical clutch fan is a headache and wallet drainer.

If you want to end this all together get an E-fan. There are pro's and con's but you would not have what sounds like a Tornado under your hood ever again.