6L w/automatic trans,no tunes,no mods. Fan doesn't speed up when ac is turned on. I checked connector at fan shroud and #25 10a fuse and wanted to see if theres anthing else I can do or check before taking it to dealer. I haven't towed heavy since I noticed ac not cooling at idle but last time I did tow the fan ramped up on hills and stop and go. I'm in Texas so I must get this right asap. I heard of some with manual override so I would like to do that as well but also heard rumors the override can damage pcm. Anyone know about or using manual override?

 

Do you have any kind of monitor to see if the fan is actually being commanded to a higher speed or if it's even reaching temperatures that warrant it being commanded to a higher speed?

 

Are you saying the air conditioning isn't getting cold at idle speed? Is that your issue? I'm confused because when I look at fuse position #25, it isn't used. Position #23 is a 20a fuse for climate control. Position #24 is a 15a fuse for tow/haul, blower relay and Auto Temp Control (EATC). Underhood, #2 is a 40a fuse for the blower motor and the blower relay is in position 303. #17 is 10 fuse for the A/C clutch relay and that relay is in position 203.

 

Turning on the A/C alone will not cause the fan clutch to lock in. ECT, EOT, TFT, and maybe IAT all play a factor in commanding FDC/ fan clutch duty cycle.

To manually engage the fan clutch you would need to ground the dark blue wire in the fan wiring connector:
https://www.ford-trucks.com/forums/1...l#post14000787

If grounding that engages the fan, I would think checking the charge on the A/C would be a logical next step.

 

I have read of guys using the method to engage the clutch with a switch. Not sure how but it's been done, similar to what you see on a lot of OTR semi tractors. I know every one of them on the farm has one, but about the only time I have ever used it was when I knew I was about to work the snot out of it climbing a long grade, would just engage it a half mile ahead of time to give it a head start on cooling.

Not sure what this would do the the PCM on a 6.0?

Edit..........I see Bryan already answered the question, props.

 

is the wiring intact all the way down to the fan clutch? I had similar issue, plug by the top of the shroud looked ok, but turned out the fan blades had cut the harness lower down where I couldn't see without removing the shroud

 

Do you have any kind of monitor to see if the fan is actually being commanded to a higher speed No,will SGII or Insite detect that command? I was aware they detect rpms. or if it's even reaching temperatures that warrant it being commanded to a higher speed? Since new 2004,the fan always sped up when ac was turned on at idle. It's bumping 99F in Texas and after 20 hi-way miles running ac the there is very liitle air coming out at alternator with air on at idle.
I'm confused because when I look at fuse position #25, it isn't used. My 2004 owner's manual say's "Location 25,10A,4-wheel anti-lock brake system(4wabs) module,variablefan control(vfc) (diesel engine only)"
If grounding that engages the fan, I would think checking the charge on the A/C would be a logical next step. AC cools fine at road speed,I think charge is ok.
Not sure what this would do the the PCM on a 6.0? Yea that's why I'm not ready to do the mod before knowing of possiable harm if any.
is the wiring intact all the way down to the fan clutch? Wire is intact and plug isn't damaged ,the fan engages but not turning as fast as it should for ambient tempature.
Sorry if it sounded like I was complaining of poorly operating ac,I'm not,the ac is only a subtle warning of something far more serious if the driver is paying attention. Truck runs fine and ac is ice cold at crusing speed but I know refrigrant pressures would go through the roof at low speed,stop and go if I didn't turn it off. I spect if I just kept on flogging it the ac would blow something fairly quick and engine wouldn't be far behind.
Thanks for all the advise,I'll take all of it into consideration while looking for a solution.

 

Ambeint Temp MPH AC rpm ECT EOT TFT


I watched it for along time I found with Mine that the threseholds mentioned above for FAN to ramp up or down its speed
I definatly found exact FAN Step points




we had a thread going Ill try to fine it

 

Fill out a signature line with your truck info like year, model, miles and any things you've updated. It helps to point you in the right direction instead of giving you info for a 2006. Lol.
Also fill out your location information too, if you haven't already. At least put in the state so guys will know if they should reach out to you to help locally.