[smagown]

The air brake antifreeze did the trick. I put it in the hose coming off the engine compressor. I let it run about 15 minutes to no avail and the pop off valve popping away.. I added a few more ounces and let it sit about 10 minutes and it built air upon starting.
All of the fifth wheels have skirting here but none of the full time motorhomes.

Thanks for all the sage advice. I never thought I would enjoy a toilet flush this much. I had been sneaking over to the campground restrooms as I didn't won't anyone to know my mighty Newell wouldn't function.