My dad has a '13 F250 CCSB 6.7 w/ 10k miles. I drove it the other day for about 30 miles in 90 degree heat and the AC on. The engine fan seemed to stay engaged the entire trip. Motor nose from the front of the truck was quite loud increasing with rpm to a roar at 3 k!. I even secured all climate controls to see if it would turn off, no joy.

My personal '12 F250 cclb 6.7 w/ 20k on it does not act this way. I just pulled six tons 1500 miles with temps reaching 100 and the fan never engaged.

I hover around 20mpg empty, dad only gets 15mpg empty. Could this fan problem cause the mileage difference and how to fix it???

 

clutch fan sounds faulty. They had stuck before. Also the reason for the poor fuel economy.

the tech can manually cycle the clutch fan to determine this issue.

You might try to go out to the fan with the motor off and see if you can turn it. I would not force it but is should spin freely.

 

Senix...I'll check that. I looked for a fuse, but it appears to be controlled by the ecm

 

Conrolled by the ECM.

 

Seems like everything is controlled by the ECM these days. I just reset my ECM so that the HVAC would work. It wouldn't allow any air to come out of ANY of the vents, not even defroster ones up by the windshield. A reset of the computers did the trick. An OBDII and Forscan (which is free) was all I needed.

It's a scary time when now your car has to be "rebooted" for it to work correctly.And don't fret - our GM car has had to been "rebooted" as well.

 

My '11 fan clutch went out. It was under warranty and dealer replace it.

 

Went and rotated the fan by hand with the motor cold and at operating temp. Had the same resistance to turn, but did rotate at least. Now to convince my old man a trip to the stealership is in order.