Occasional 'Hissing' Noise While Driving

[FlavourShot]

I've had this sound for a while but never bothered to ask about it because it doesn't seem to be causing any issues.

It sounds like a tight suction of some sort. No way I can get a recording because it happens very randomly. It's very audible through my interior's AC vents?

 

[joegr]

Usually, that is the expansion valve, and usually it means you are kind of low on refrigerant.

 

[FlavourShot]

Usually, that is the expansion valve, and usually it means you are kind of low on refrigerant.

Ah, so could there be a leak in the expansion valve that's causing the low refrigerant? Is that how it works? Also while i'm here I may as well kill two birds with one stone:

Looks like I have an oil leak out of the lower IMT? As far as im concerned it's caused by a bad gasket, just looking for your assurance.

 

[joegr]

The expansion valve is very difficult to change out. The entire dash has to be removed.
Dash Board Removal Thread
It's very unlikely that the expansion valve is leaking. The most common leaks seem to be the o-ring on the cover of the scroll control valve and the low side fill port or high side pressure test port.

 

[FlavourShot]

The expansion valve is very difficult to change out. The entire dash has to be removed.
Dash Board Removal Thread
It's very unlikely that the expansion valve is leaking. The most common leaks seem to be the o-ring on the cover of the scroll control valve and the low side fill port or high side pressure test port.

Good lord. If that's the case, the noise can stay. Do you have location images of the ports you mentioned?