2010 xc90 AC engine noise 165K Topic is solved

[raquette]

from what is posted on various sites, sounds like this noise may be a faulty alternator decoupler pulley. appears the alternator must free wheel in the unloaded direction. the noise is coming from the coupler block area.

[raquette]

I see on other forms the two decoupler pulleys can make this noise. one on the alternator and the other on the lower serpentine at thge rear end assembly drive (READ).

[raquette]

found on other sites there are two decoupler pulleys - one on the alternator and the other on the serpentine belt side that can make the noise I am hearing.

not sure how to determine which one is failing.

[raquette]

on another site it was mentioned the decoupler pulley on the belt (serpentine) side is bad if you cannot rotate the air compressor pulley in one direction when the engine is not running.

would someone who has a pre 2011 xc90 3.2 try that and report back if your ac pulley free wheels when spun backwards?

thanks

[raquette]

well it ended up to be a bad serpentine coupler pulley under the air conditioner. the bearing was rattling.

great repair by the local volvo dealer.

[Capndirk]

"would someone who has a pre 2011 xc90 3.2 try that and report back if your ac pulley free wheels when spun backwards?"

I have a 2009 3.2, the belt as it rounds the AC compressor can be pushed towards the front of the car in freewheel.