Compression Ignition Addict
Join Date: Dec 2007
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Couple of things......
First, if the hubs were stuck in the LOCKED position, then why do you think it's the hubs that might be the problem in getting you 4WD? You could get a quick idea if they're really locked by climbing under the truck and turning the ft driveshaft by hand (in 2WD).
If they were both locked you couldn't turn it. If you can, look at the U-Joints behind each wheel to see if one of them is turning. If it is, jam a long screwdriver in it and see if it either locks the driveshaft or makes the other U-Joint spin.
Next, if you can't move the hub selector at all then, they at least need to be pulled (easy job), cleaned, and re-greased.
Then to test each hub again and see how they are Locking-UnLocking you could then jack-up each side, one at a time, and watch the driveshaft.
With the TC in 2WD it should turn very predictably with the tire.
With the TC in 4WD you shouldn't be able to turn the wheel at all (unless the other side wasn't locked, but you'd see the U-Joint spinning over there too)
There's also the possibility the "shift motor" in the TC isn't actuating. This too can be pulled and checked for movement.
Also, I believe a Warn replacement would convert you to manual only hubs, I don't think there are vacuum actuated replacements except from Ford (I could be wrong....)
Not sure what the electric fan could have to do with all this, vacuum problems with heaters are about doors (to direct heat around) more than the fan.