Terrrible squeal under hood. Replaced both idler and tensioner pulleys. I suspect the AC compressor.

Can I replace the bearings in the compressor? Or must a remanufactured unit be considered?

If the refrigerant is low, can this cause the squeal?

I think the squeal problem is not in the alternator or the power steering pump.

Any suggestions welcome. Thanks, Pat

 

If it makes noise when a/c isn't cycling it could be the a/c compressor clutch and not the whole unit. Did you replace serpentine belt when replacing idler?

 

I disconnected the AC compressor and the squealing continues. I did not replace the belt, it is in good shape, and am certain the belt is not slipping.

 

Is is a slipping belt squeal or a dry bearing squeal? Belt squealing can be checked by applying lubricant to the belt surface for an instantaneous check. Such lubricant would be water or non-oil dressing. Most dressings are coverups for failing belts, and are useless except for testing.
The bearings on the alternator, water pump and power steering pump can be checked by turning the pulleys by hand, and feeling the resistance and smoothness of operation.
Your tensioner could be mal-adjusted if adjustable.

The A/C compressor clutch has bearings that allow the pulley to rotate freely when the clutch is disengaged. These bearings would squeal all the time until the clutch was engaged if faulty. The bearings are not in use when the A/C compressor is turning.
tom

 

Is the water pump directly behind the cooling fan on the same shaft?

 

Try removing the belt and turning the accessories by hand to find the offender. And yes you can add water pump to the list.

 

Apologies for wasting your time. The squeal was like I had not heard before. It sounded metallic, like dry bearing, and I would have bet $50 it was bad bearings in something. I replaced both the idler and tensioner pulleys, just happened to have them on hand as back up, to no avail. I was convinced it was the water pump. Took it to my mechanic who simply sprayed some belt dressing on and deduced bad belt. And I even had some belt dressing (not a fan of this stuff) and could have done this simple test. I bought a new belt and put it on and all is fine. The previous belt was a high quality belt and probably only about 2 years old, it looked fine, no cracks, clean, etc. I never doubted the belt.

In any case, problem solved. And your recommendations were spot on which I should have went with instead of my diagnostics.

Thanks.