Unless you have a QEV the solenoid should vent a small amount but really only when it cycles.
With the air off can you hear a faint click from the noid when trigger is pulled?If there's no click the noid is probably dead.You can also check with a volt meter on the backside of the board when the noid is soldered to the board to confirm if the board is actuating the noid
If it does click the noid and\or banjos may be plugged with a piece of shell or dirt.It can be disassembled but note how the disk\diaphragm(?) is oriented.It has a few small parts and not easy to do if you're not mechanically minded
Reg spikes are killers for these noids,consider a reg rebuild if you replace the noid if it's bad and the reg hasn't been rebuilt recently.
ballin' since '95
REAL modders are on M Carter Brown