Hi,

My Girlfriend drove my F150 over to Naples, FL which is about a 3 hour drive. She noticed a vibration coming from the engine (4.6L automatic 4x4) when she got over there. There is no knock just a vibration and there is no lights coming on. She drove it back without any problems. But I'm still getting the same shake. When I was looking in the engine I noticed that the belt tensioner was shaking too. I put the A/C off and it went away, it stopped shaking. I was wondering if anybody had this problem before? Do I need to replace the A/C compressor clutch? I just replaced the fan clutch on it. I read something about a switch doing it. Do you have any suggestions?

Thanks,
Bill

 

I have a 2007 F-150 with the 5.4 engine and had the same vibration when the A/C was on. Ford said it was the tensioner, but that didn't make sense to me. So I replaced the a/c compressor and the vibration went away. The bearings were going bad causing a tight spot that caused the vibration. I've seen this problem on several forums, but no one came back to say how they finally fixed it. So here's the answer!!

 

How old is the belt and tensioner: The tensioner should be replaced whenever the belt is replaced.


It could be the A/C clutch, but I'd want to know for sure before I toss a new one at it.

 

Bucko, I replaced the belt last fall when I replaced the plugs. The tensioner is original to the truck. Never heard of replacing the tensioner with the belt, and the Ford house didn't recommend it. With 128,000 miles, and to save time and money, I thought it best to replace the compressor rather than just the clutch. In this case it was a good call, as the bearings were clearly bad.

 

No worries; if it's bad, then it gets replaced. Most A/C compressors have the ability to have just their clutches replaced instead of having to open the "system" with a complete compressor replacement.


I've always replaced the tensioner with a belt replacement; strange that the Ford house did not recommend this.

 

It seems like it's a common problem with the F150. Mine is doing the same thing. I talked to a mechanic with an 07 F150, he had the same problem. It's the A/C compressor.

It sucks, my truck only has 67,000 miles on it. I never in my life replaced a A/C compressor with this low of mileage. I had other cars with over 150,000 miles with the original compressor. Ford needs to step up.

Thanks for the help.