Hooov Noise - SOLVED

[Guacamole]

So I was making a right turn at a stop light when I heard a loud "hoooooov" metal-grind noise that sounded it came from the Baja, but I thought it was the semi-trailer next to me. Today I heard it twice, once while braking & again while just regular driving. The issue so far seems to be intermittent but from what I can tell it sounds like it's coming from either the rear left of rear center. I had the rotors & brake pads done by a subie tech about 5k miles ago. I had a suspicion that it was the rear left brake until I heard it without using the brakes. The sound seems to immediately stop when I release the brake or accelerate or coast. I've looked over the brake discs & there doesn't look like there's any serious wear or grinding going on.
Could the rear diff be the culprit or would it be something simpler like an axle or drive shaft, or could it be the brakes?

EDIT: Heard it again today, this time it actually sounded like it came from the brake pedal. Maybe it just needs a little oil or I put my foot on it the wrong way.

[anarchy1024]

Have you noticed any other patterns when the noise happened? Like, were you turning, had extra weight on a particular side, ran over something on the road (not necessarily debris; could be some road repair), specific gear, or anything that was common between the times you heard it?

[Guacamole]

I have discovered the source! The only thing in common between every time I've heard it was A/C was on- and thus is the culprit. I was playing with the A/C and discovered I can reproduce the sound after I switched between 0 & 1 on the fan switch while idling. The sound is directly coming from the passenger dash & the air controller unit under the dash vibrates when the sound occurs. I recently had the A/C flushed & recharged so they probably did something in there, I have a feeling that one of the internal fan motors/blades is rubbing. I'll probably pull the cabin air filter & look inside the unit to see if I can find the true culprit.

[anarchy1024]

Congratulations! This is relatively good news, at least in terms of severity. Those cabin air filters aren't the easiest to get to, though...

[Guacamole]

Yeah I watched a "how-to" video, I might just take it back to the dealership that did it and yell at them until they fix it.

[anarchy1024]

It's probably best to bring it back to them, anyway, just in case it's something you can't fix on your own. You don't want them to invalidate the warranty because you tried to fix it yourself...

[Guacamole]

So it turns out the issue was they overcharged the A/C & the whole system had too much pressure which was causing the noise & the entire unit was vibrating. So they drained & recharged the A/C again & it's actually colder than when they recharged it the first time.

[kamesama980]

In the world of refrigeration, more refrigerant is not better. It's broken. It also destroys the credibility of the person doing the AC work, it's NOT that hard to correctly recharge an AC system even without tens of thousands of dollars of equipment.