I have an 2003 ho and have had my fan lockup at times that i thought that it should not have, and wondering how the fan works on the 03. Is it computor controled, viscous or both? is it part of the 7/70 power train warrenty? I bought the truck new and never noticed that roar for the 1st 5 yrs that i owned it. Now it seems it locks up about any time. I have read about all of the threads i could find on this but none of them explained this for the 03. Any input will be appreciated. I did read somewhere that there is a spin test when cold the fan should free spin about 3 times, mine does not.

 

Your fan should not free spin that easily. You should be able to spin it but with some resistance. Activation is computer controlled. The ecm monitors engine temp, IAT, & AC pressure to determine clutch engagement. Do you have a winter front installed ?

 

Do not have winter front.Its just strange that i never heard that fan even pulling small rv across country, and now just having the defroster on first startup of the day and it locks up. It does disengage at about 48mph and i think thats normal.
My fan will not spin at all by hand turning.

 

It is normal for the fan to engage at slow speeds with the defroster on due to ac activation. The fan should turn by hand but not coast and not easily. Upon starting a cold engine it may also engage as the silicon is being redistributed but this shouldn't last more than a minute or so. If you've checked the coolant level and the fins of the intercooler, radiator, and transmission cooler are clear. As long as your temps are running normal I wouldn't worry about it. Sorry I'm not more help

 

the fan is computer, fiscus controlled. Yes it will engage with the defroster and or ac is on. If you still hav ea warrenty then take it the dealer and have them perform the fan diagnostic test. Worst acast is they need to replace it and or the ECU.

 

I stopped at the dealer a couple of weeks ago. The diesel mechanic was off that day but another mechanic pulled up the diagnostics/trouble flow chart and i think i remember it said while cold spin fan and should spin free. But i am not sure that we were looking at the correct info for my truck. I did watch while he looked it up and im petty sure it was for the 03 .

 

I would like to know if anyone has put a switch on it were you can lock it up when you want to. Like when you are backing up to move more air across the cooler.

 

Still looking for more info on fan. is it covered under 7/70? I did get to talk to the diesel mechanic, he pulled up diagnostics , it says when cold it is normal to spin by hand 5 rotations, mine will only move about 1/4 of a turn.

 

mine spins free by hand when cold havent tried i thot though i am having fan issues as well but i dont really care all that much the truck runs fine and gets up to temp