What our world needs is another X350 air suspension thread but:
2004 XJ8 suspension rises to maximum height and will not lower unless I bleed the air through the lines.
It would then rise to maximum again over the course of several minutes.
I can hear the compressor shutting off so I do not think it is relay issue.
Any thoughts?

 

There is no vent to allow excess air out of the system except a solenoid at the compressor. That valve is very susceptible to rust if water gets in the system (and it does.)

To lower a strut, the system opens the valve between the strut and the reservoir, along with the valve on the reservoir that faces the compressor, and simultaneously opens the vent valve on the compressor. Three valves all have to work.Since the car raises if you drop it, the valves at the reservoir are probably OK. But air CANNOT escape the system (except though leaks or disconnects) except by way of the compressor's vent solenoid. Not an easy thing to inspect, as the compressor must be removed and disassembled.

 

I agree and thank you for the reply. This is now my son's car and we are remotely diagnosing. I am having him put a voltage across the solenoid terminals to see if it will activate. It won't be until the weekend. BTW, yes I could be the reason.