Hello, I have tried searching for a similar problem with no luck. Today I had my fan clutch replaced in my 2005 f-150 5.4. Now with the new clutch, I have gone from no working fan, to a fan that doesnt shut off. Going 80 down the interstate the fan just roars on.. Any ideas on why its doing this? Thanks in advance.

 

Take it back to whoever did the work.

 

you got a bad part. Make them fix it.

 

Alright i'll go check back with them then, you dont think the thermostat is bad or anything other part though?

 

If the thermostat were bad, your temperature gauge would show it.

 

Its not an electronic part. Just a clutch. not thermostat control

 

I'm not 100% sure how a clutch fan works but I was under the impression an automatic clutch fan is controlled by temperature. Thermal transfer from the water pump side. Some kind of heat element/metallic coil majiger thingy mababbor that controls some type of hydraulic silicon fluid in the clutch assembly. So... if a thermostat were bad, more heat would build up on the pump side causing the fan to stay on. But like glc said, temp gauge would show something. I bet it was bad out of the box.

 

The fan is in fact thermostatically controlled - by a thermostat in the clutch assembly, not by the engine thermostat.

 

The thermostat on the fan itself reacts to the heat coming off the radiator. Which is typically why all clutch style fans have shrouds.

 

isnt it just a spring?

 

Nope, there is what looks like a little spring in the front center, but that isn't how it works. The heat from the radiator passes back over the outside of the aluminum fins on the fan clutch. That in turn expands the aluminum and causes it to contact the opposing set of grooves in the engine side of the clutch. (I have done a terrible job of painting a word picture here) There is VERY little gap between the 2 opposing sides, and it is bathed in some form of oil inside. The picture, in a cross section, would be like you passing the fingers on your R hand into the same openings between the fingers on your L hand (on a flat plain) except the grooves are round like a cut off section of pipe, rahter than a flat plain. Don't know if even I could understand my own word picture, but I've seen plenty of them smashed apart, and that's the way they work. The '07- up DO have an electrical connection to them so they are obviously different, though I don't know the details of how THEY work.

GLC and Wraith's answers are PRETTY close to accurate.