Is the initial 12volt supply to the compressor via the relay controlled by a timer or sensor of any sort?
Compressor starting up inconsistently when disconnected from air bags, not under pressure and running from anything from 10 secs to a couple of mins

 

Height sensors control suspension. Have you seen if there was errors in the system. Was it disconnected while the battery was still hooked up

 

There are no leaks in the system, the suspension stays up for 2-3 weeks at at time without use. WHen vehicle moved the suspension may go down. Having removed compressor and the pressure switch, with the completed disconnection form the air bags and the pressure switch removed form the compressor I think everything should indicate the system needs pressurising but the compressor will only activate every few mins sometimes for 15 secs or up to a minute and stop again. THe relay seems to be functioning, is there anything else that controls the supply to the compressor, Where are the height controls sensors? CHeers