I've never had the problem of the compressor running when it shouldn't (only the problem of the air not releasing), but looking at the wiring diagram, it seems to me that an air leak, by itself, should not cause the compressor to run on a parked car.
I could see how an air leak, combined with a faulty ride height sensor could do it. My understanding is that with the car on level ground and empty (no people, or cargo) there should not be any air preasure required in the system for the car to sit at the proper ride height, so the compressor should never need to run. But I could see that if there is something wrong with the ride height (i.e. rear springs "worn" from age/use) or ride height sensor faulty or out of ajustment, that it could trigger the compressor to try to level the car. When the sensor thinks the car is level, the compressor would stop, but then if there'* a leak in the system, the air would slowly bleed, the rear would drop,and eventually the sensor would think the car needs to be leveled again, and restart the compressor. Could this be what'* happening?
1995 White Bonneville SSEi