[Burlyman]

I can say that on mine I had a faulty transmission modulator which was allowing air to blow past the seal and into the transmission fluid. I only found it when I was under the coach and heard gurgling in the trans pan. Part was $130 and is supposed to be replaced at every transmission fluid change. Compressor went from running every 30 min to over 4 hours

Fascinating... This is something that I would have never suspected.. I guess I will listen for some gurgling then.  Thanks for the info!

Williams WM775B is the modulator my transmission used on my Wanderlodge with my MT654 transmission. I have heard a couple of folks had this same issue in the Wanderlodge group. 

This of course only applies to those who have an air throttle.

I also heard of a guy that had an air horn that was stuck on, would not allow the coach to build air and was not enough air to toot the horn. He about went mad trying to figure that one out. Our air horns are on the roof and he just happened to notice a slight sound from the horns.
Food for thought, air leaks could be anything that takes air.

I have also heard of systems leaking back through the compressor too.

Excellent food for thought.  It's not an emergency situation by any means, but I guess I will just start checking every spot that air goes to or from, listen closely, and use a spray bottle of soapy water where I have access.