I am afraid that you do not give me much to go on here. I do not know what year or model your motorhome is nor do I know who manufactured the Air Suspension System on your RV. It really does not matter though as I would still end up giving you the same advice.
About the only thing you can check for is for any blown fuses for your air suspension. There is not really a lot that a do-it-yourselfer RVer can do to properly diagnose and repair the problem you are having with your Air Dump.
If you do not find any blown fuses the problem could still be the rocker switch, a bad or loose connection in the system itself, a shorted wire or a bad system control box.
I am afraid that you are going to have to take your RV to a mechanic that is equipped and trained to diagnose and repair an Air Suspension System.
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