My Subaru Is Making A Strange Noise, I Can't Find The Reason (EZ30)

[patrickcortes10]

My Subaru is a 2008 Legacy with an EZ30 engine, and it's making a noise I can't figure out why. The noise is on the left side (looking at the engine from the front), on the side where the air filter is located. The noise occurs below the intake manifold, and it appears when the air conditioning compressor activates, however the noise is on the opposite side where the compressor is. I have already changed the belt of accessories, pulleys and others, but nothing solved this noise. Another detail is that sometimes even with the air compressor activated the noise does not appear. In person it sounds a lot like a compression sound being lost. I recorded a video and posted it on YouTube, link below: