98 Nissan Sentra accessory belt whirring noise

[wirelessF]

Working on my uncles 98 Nissan Sentra 1.6L trying to figure out an accessory belt drive noise. Car has two belts: 4 rib belt driving water pump/PS pump and 6 rib belt driving A/C compressor and alternator. Removed the 6 rib belt (keeping 4 rib belt on) and noise disappears. Replaced alternator and noise still persists.
Belt is extremely worn so planning to replace it too.

Looking for other opinions on what the noise could be.

 

[renegade_987]

Could be a compressor bearing in the A/C, and could also be coming from the old worn belt. Start with that and see if the noise persists.

 

[Drew99GT]

Grab the water pump pulley and wiggle it with some force so as to see if the shaft bearings have any play. If so, that's the problem.

 

[Chris142]

Put water on it while its running. If the noise stops its the belt.

 

[HTSS_TR]

Originally Posted By: Chris142
Put water on it while its running. If the noise stops its the belt.

+1

 

[Nayov]

Idler pulley. I've replaced those a time or two back in the day on those due to noise complaints.

 

[wirelessF]

Replaced the belt and noise is still there. Got a a real mechs stethoscope and pinpointed the noise to the A/C compressor where the whirring noise is louder. It's with the A/C off so A/C pulley bearing must be replaced.