OK, I have just had what must be about the dumbest damn thing I've seen in a spell. I went to winterize the 7 month old 5th wheeler and decided I would blow out the lines and then circulate a little RV antifreeze for good measure. So I hooked up the air hose to the "city" water supply hose fitting. For the life of me, I could not get the plumbing to take air.
What gives? A checkvalve or something go bad?
And for the smart alecks, yes I did open the faucets and no, it was nearly 55 degrees while doing this so it isn't frozen. For a while I was able to hook up the garden hose and get some water into the plumbing, but only a trickle.