I have at least one low shock (rear), not sure how to diagnose if its the compressor or the shock itself ?

Any ideas ?

Also,
is there a problem with running without the compressor, if it turns out that it is the problem ?

I assume the low shock is on the passenger side, because if it was on the driver'* side, it would be activating the level sensor on the driver'* side, causing the compressor to run.....

If there was a leak, then the compressor would be running most of the time......chances are you have lost all the fluid in one shock, causing it to be low......

Is there a way to test, or check to see if the compressor is working.
The link and switch don't seem to be damaged.....

A year or so ago, I remember hearing it a lot, it ran off/on quite a bit, would run for a minute, ever 10 or 15 minutes....

Thinking about it now, I haven't noticed it running at all.

Also, seems like you shouldn't have been able to hear it, but it was noisy enough o hear.

and where is it located ?