I'm having to bring my truck in tomorrow to the dealer to see why I feel the truck is bouncing me around when I'm sitting in drive at a red light or anytime I'm sitting when the truck is on.
I'm wondering if my engine fan is ever going to shut off anytime? It's always on! I start up in the mornings and it's full blast when it's -20 out! It clams down a little, but when it clams down, it always goes from very slow, to very high speed, to very low again and back up to high again! Whys that doing that? Is that normal? Never once since I had this truck did I ever hear the fan off. It just sounds like it's always going from fast to slow constantly. Can anyone help me out here?

 

What's happening is normal. The fan is controlled by a clutch mounted on the front of it. This clutch is controlled by engine temp. as the air moving through the rad heats up, it causes the clutch to lock up and engage the fan.

When the engine is cold (after it's been sitting for a few hours), the oil in the clutch settles to the bottom. This causes the fan to engage until engine RPM distributes the oil and everything starts to work normally.

Nothing to worry about.

 

"Engineering is aware of the concern and is currently working on a solution. Monitor broadcast messages and OASIS for updates."

If you're hearing something like a rolling idle coming from your fan, that's Uncle Henry's answer to it.

 

TBird-
Best explanation I have heard yet. I couldn't figure that out for the life of me. Our 97 Suburban does the same thing. Thanks-

 

No problem. Glad I could help.