AC related screaming noise from engine compartment

[maccalo]

My car recently developed a screaming noise coming from the aux belt area in the front of the motor compartment. At first I thought it was a dying AC compressor, since it has been blowing sparse with cold air even when regassed, but can this be related to other components? (aux fan?). The noise is RPM dependent. Car is a 1.9 TDi.

The sound initially came after a 20 min drive, and immediately went away when turning the AC off. At idle I could reproduce the symptoms by turning AC on and off as shown in the video:

[egovreau]

I couldn't quite tell and don't know much about the TDI. Does that belt drive anything other than the AC? Could be a loose belt.

Sent from the 7th Galaxy.

[john_gonzo]

A stethoscope would help narrow down the source of the noise. By "stethoscope" I mean a meter of hose or tubing.

[maccalo]

Another video



Now I'm starting to think it's the turbo? But why would that be so closely related to the AC?
This engine has a separate AC belt. Booked at local garage in a few days...

[diagnosticator]

It could be the belt slipping, or one of the idler bearings in the belt run circuit. With the engine idling, spray the belt with a garden hose lightly, just enough to wet everything, if the noise stops with the belt wet, then that is solid evidence the belt is slipping, with a faulty belt tensioner. A noisy bearing will also get quieter if flooded with enough water to lubricate the bearing temporarily, this would be the case if the bearing/s where worn out with dried or no grease inside.

[old guy]

That isn't a turbo noise. You have a bearing somewhere going bad. It's probably your AC compressor since changing the compressor load changes the noise. But it could also be anything else that changes load with the AC on or off. I had a similar noise when the bearing went out on my water pump.

[demonmk2]

I had the same problem/noise once.
It was the a.c. compressor ( bad)

[maccalo]

Thanks to everyone.

Final diagnosis: Seized AC compressor.

Replaced and running sweet. It must have been making pretty much resistance on the belts. The car now feels a tad quicker!?