Ad9 Air dryer purges every 2 minutes

Sorry, I hope you didn't read that last post. Take the black plastic cover off the back of your governor. There's a nut. Loosen it. Turn the "bolt" inside the nut clockwise one full turn. Snug the nut back down. That should drop you to the 104psi range. If that works, tweak as necessary. Mine cuts in around 95psi.

 

Check out this thread too, if you haven't already.

is my air governor going bad?

 

When the air pressure reaches the governors preset pressure 125 PSI it opens
internally and momentarily letting air into the discharge port. The air supply from the governor is not continuous its just a quick burst that unloads the compressor and
discharges the dryer. When the pressure drops to 100 PSI the governor exhausts
the air and the dryer closes and the compressor starts pumping again.
If the air from the governor leaks off the compressor will start pumping again until
the governor discharges again.

Some of the equipment that I once worked on had 2 Bendix compressors and
2 AD9 dryers to supply enough air to run the clutches and brake bands and winches.
One governor did not supply enough air to unload 2 compressors and 2 dryers reliably
so we used to install a small relay valve that the governor controlled and the relay
valve supplied constant air to unload and discharge.

I suspect the rattle snake sound you are hearing is the unloader valves in the compressor
hitting the valves as they retract with the air leaking off. If your compressor starts pumping too soon the air has leaked off. Its either leaking in the dryer the governor or
the compressor or the line from the governor to the compressor. You could plumb in a gauge in the unloader line and see if its dropping. Its probably a 1/4" plastic line, it
wouldn't be a big job to run a new line.

 

Did you figure it out?