Sandpaper or hissing sound in engine bay

[Kyngfish]

Hi all,

Looked around a bit, and I'm getting this faint hissing sound out of the left side of the engine bay. It goes in time with the revs and doesn't seem to come from the engine, could it be the AC compressor? Best I can describe it, it sounds a bit like someone moving sandpaper quickly across wood, or like a really faint maraca

New to this car, just wondering if there's something I can pre-empt or look out for.

Best,
Martin

 

[kball]

The ac idler pulley is known to go out sometimes and make noises.

 

[Kyngfish]

Thanks

Definitely in the right place for the sound. I suppose if the bearing is going it could make that sandpaper sound.