Originally Posted by MVP
How do I dump the compressor tank?
It can vary by manufacturer, but there are instructions in your manual. These are supposed to be pulled by you periodically to ensure there is no moisture in your tanks. Should have been covered in PDI when you bought the coach.
In my case, I have a Freightliner, and there are three tank purge valves, the tanks are which are mounted in the center line of the coach, up near the front of the coach. I have three wire lanyards, which extend from the tank purge valves thru the frame, and exit by the front tires, two on one side, one on the other. If you turn your wheels, they are easier to see. Pull each lanyard, and you'll hear air escaping from the purge valve. If you hear water spitting out, bad news and there is an air filter in the compressor line that you need to get changed. When you compress air you also get water, and that filter is what makes sure none of the moisture gets up into your three tanks.
Use those lanyards to dump the air completely from all three tanks before putting on the shutoff valve.
If you can't find the lanyards, then crawl under the coach from the front (while it is on blocks) and visually find your tanks. Find the purge valves (low point on the tank), and follow the lanyard to where it exits to where you can grab it from the outside.