Hi ZZR, yes i still have the comp but when i tried that the air just blew out of the exhaust valve on the valve block.
The compressed air should enter the valve block and be directed to either the airbags or the air reservoir tank , it should not be vented to atmosphere, if the air is coming out of the exhaust valve filter you may have an open/stuck valve.
You have tried connecting your independent compressor to the valve block which seems to rule out a compressor fault (at the moment), but if the compressor has run for a very long time the piston seal may have been damaged by over heating.
I would personally now proceed as follows:
1. Using the independent compressor, remove each airbag supply pipe one by one (possibly from the main valve block) if the airbag lifts, move on to the next one. If you have access to 4 axle stands support the vehicle while doing so, this will make checking the overall system condition easier, if all corners have been raised/supported and airbag condition checked, move on to the valve block.
WARNING NOTE. By using the above method there is no limit to the height/pressure available, so an airbag could burst/collapse with dangerous results.
2. Disconnect all electrical connections to the control coils on the suspension manifold block, supply air from the independent compressor to the air inlet port, if the air is escaping from the exhaust port, I'd be looking for a leaking/stuck valve spool (the reason for disconnecting the coils is the system self check/adjusts the vehicles height every few hours even with the ignition switched off).
If no air leak reconnect the valve coils and turn on the ignition, if the leak returns you have an electrical control problem.
3. You should now have isolated the main problem, why the suspension will not raise and hopefully carried out the repairs. Now refit the vehicles air compressor if the system doesn't lift you may need a compressor rebuild....