A couple days ago I was told by our engines instructor at school that Ford had a problem with some Fan clutches on the 99-03 f 150s. He said that they would actually cool the engine too much and not let it get up to operating temperature. Has anyone else heard of this?

 

That's completely impossible with a thermostat installed!! Your engine will (or maybe I should say "should" just in case) never run cooler than the thermostat...Hense the purpose of a thermostat...to close off and block/reduce the flow of water as necessary to maintain a certain temperature within the engine.

Is there a problem with the fan clutches?? Don't know...never heard that one. Even if there is, will it make your engine run too cool?? Never!!

 

They can lockup and cause unecessecary drag and cooling on the radiator itself but will not cool the engine too much really, as Galaxy stated, the addition of a thermostat changes things alot. My clutch never gave me a bit of trouble but I went with electrical fans to save on gas mileage and of course pickup the additional HP as an added bonus!