I think I have a leak in the rear right air strut (at least the leaking air sound is coming from that area), but the whole car seems to lower. I didn't think that was how the system worked. The car will also sometimes make a very high pitch air leak sound on the right side of the engine (sitting inside the car) when it's running the air compressor (the compressor is on the left). The car will raise to a driveable height after turning the car on and off (the compressor seems to have to run twice). At first I thought I had an air tank issue, but the sound near the strut made me think it was the culprit. This all this started after I lifted the car to check the brakes, but maybe it's just a coincidence

Maybe it's also time to just go with springs - the Suncore set is about the same price as two rear air struts..

 

I believe one leak will indeed affect the entire setup due to the self-leveling feature. Confirm the leak using soapy water. Also keep in mind that the PCV valve is on the right side of the engine and makes a loud hissing noise.

 

Yes, one leaking air strut will affect the whole car. The car will continue to lower the remaining struts to keep the car as close to level as possible. The reason is that if it didn't the car would experience wobbling or swaying when hitting dips or bumps on the road; not safe.
Try to catch the car before it completely bottoms out to see which corner is the lowest. Other than that you can let the car raise itself then turn off and disconnect the battery; this will prevent the system from trying to level the car thus highlighting the droopy corner.

 

"The car will continue to lower the remaining struts to keep the car as close to level as possible."

Are you saying it won't try to level the down one to replace air leakage? The entire system wouldn't work if that was the case.
(he never said the leaking one was "stuck")

Nevertheless, if you can hear leaking air, you know you have to do something.

 

If the car is on then it will try to raise the down strut to maintain the car level. If this occurs excessively the car will give up and result to lowering the other corners.
If the car is parked and off it will resort to lowering rather than raising to maintain level plane.

 

Ahhh...is the high pitch sound something I should be concerned about? is the regular hissing normal?

Great idea! I'll try that once I get the wheels back on (currently working on rear bushings etc)

 

Yes, the PCV hissing is normal for these engines. Not saying that there's not an air strut leak on that side, just something to be aware of. The PCV hissing should be continuous as long as the engine is running.