2001 Ford Explorer Sport Trac A/C Compressor making Noise

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#1
Make
Ford
Model
Sport Trac
Year
2001
Miles
155000
Engine
4.0
Ive got 155000 miles on a 4.0 automatic trans. and noticed a noise recently, thought it was the power steering pump but I think its the a/c compressor its like a loud scrapping noise, the a/c blows cold and it makes the noise if the a/c is on or off and also it usually is loud when I just start it up. Could it be the clutch or the compressor itself making noise ? Any help is appreciated
 

billr

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#2
Take off the belt that drives the A/C and verify that the noise goes away when no part of the compressor is being turned. I expect this engine has only one drive belt, so taking it off will also verify if the noise is coming from some other belt-driven accessory. The water pump probably will be inop with the belt off, so do this test with the engine cold; you can idle it for several minutes that way if you start out with a cold engine.
 

grcauto

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#3
Ive got 155000 miles on a 4.0 automatic trans. and noticed a noise recently, thought it was the power steering pump but I think its the a/c compressor its like a loud scrapping noise, the a/c blows cold and it makes the noise if the a/c is on or off and also it usually is loud when I just start it up. Could it be the clutch or the compressor itself making noise ? Any help is appreciated
Not going to be the compressor or the clutch since they are both inoperative when the AC is off. Still remove the belt and see if the noise goes away.
 

billr

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#4
Not going to be the compressor or the clutch since they are both inoperative when the AC is off. Still remove the belt and see if the noise goes away.
Not completely true. The compressor pulley is still turning, even when A/C clutch is off, and the clutch faces could be rubbing (not dis-engaging fully) or the bearing the pulley rides on could be noisy.
 

grcauto

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#5
Not completely true. The compressor pulley is still turning, even when A/C clutch is off, and the clutch faces could be rubbing (not dis-engaging fully) or the bearing the pulley rides on could be noisy.
Normally if the bearing is bad it'll get much worse when AC is on and will change in noise level as the compressor cycles. If it were a dragging clutch it would be quiet when applied. I think maybe it's alternator or water pump but who knows. I guess we'll find out.
 
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#6
My $.02...Sometimes a compressor pulley bearing will get quieter when clutch place is applied, because the plate creates a side load to the bearing and also adds support to keep it spinning at center (instead of being pulled off-center by belt tension).

As others have suggested, remove belt to assess. Check AC pulley for "excessive wiggle".
 

billr

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#7
If the noise goes away with the pulley off, check all the pulleys (including idlers and tensioner).

Right now, I just want to have some confidence we are looking at the correct end of the engine, that it isn't something like a trans, clutch or flex-plate. Noises are notoriously hard to identify.
 

nickb2

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#8
Sometimes, I just can't help myself. I get caught up on terms and need clarification of terms. I had a car in the other day, was still 29C, 37c in the sun. Anyway, here comes my memory terminology.

Now I didn't read the whole thing again, but I think we may be talking about a AC comp belt idler pulley? Making noise all the time. Yes?

If and when the AC engages, the clutch does a pull in action which in most cases make the compressor idler pulley to stop whing as now the ac comp is in direct drive and relying on the shaft bearings.

So if the engine is whining even with the ac on, clutch engaged, it's most likely not the "clutch pulley".

Unless it's like the story I was going to talk about, idler pulley so far gone it melted to the actual armature of the clutch coil. Any way, screeching must have started again, client still refused to make it to the shop. 3000$ or so later. AC comp seized, in direct drive cuz clutch is melted to idler pulley, belt flew, screeching stopped, and so did this lay who thought she could drive forever with this screeching sound howling out the engine bay.
 

nickb2

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#9
She, the laydy, said it had been making noise for months. but everything was working fine. That's what happens when you ignore abnormal noise from an engine to go unchecked I explain to the lady as I gave the estimate to the sales guy. ;)