Two things of note.
1st - The air compressor must be located inside the cab or if mounted outside the cab be plumbed so it is pulling dehumidified air from inside the cab. Mounting the compressor outside the cab violates the one year warranty from Viair due to moisture build up inside the compressor.
2nd - The barbed fitting that comes in the solenoid needs to be removed and replaced with the green oval Parker Prestolok fitting. The air line will slide right into this and lock into place.