Following some troubleshooting suggestions from John Duld from an earlier post. At the point of removing the cover from the panel next to the drivers seat. Plan to use contact cleaner on the switches and contacts in there but can't see how to cut power to that panel.
Will also want to cut power to the control box mounted on the ceiling in one of the bays. Will be trying to remove and reseat all of the connectors.
Do the fuses in the bay control box control all of the power for the HWH system?
You haven't gotten much help on your question. Here is a link to the HWH Repair Manual for the system in our 1993 model couch - yours may be different. Scroll down through the manual until you find the electrical diagrams (Section 3) - may provide some answers.
http://www.hwhcorp.com/ml11148.pdf
If you want to cut the power to the HWH, your 12V master switch turned to off will do it.
Assuming your HWH panel is like ours (although ours is mounted in the left hand side of the dash), it's pretty easy to remove the connecting cable to the back - a single flat cable -, and often the connection itself is the problem, since the connector can get loose or fall out. I would start there and pull the connector out, spray the contacts, and reinsert it. If loose, try to tie-wrap it in place, or possibly secure it with electrical tape.
We took our control panel out of it's location, unplugged it, sprayed the bejesus out of it with CorrosionX and plugged it back in. It has been working fairly well ever since. We are leaving Madison, WI on Tuesday and heading toHWH in Moscow, IA for an appointment to find out why our auxillary air compressor will not shut off when it starts up to level the coach. It's always something!!
If you need something while we are there, I can try and find out who you might speak with.
My money is on the normally open solenoid purge valve not closing/being stuck open when the aux compressor starts (the valve that makes the "psshhhhheeewww" sound unloading when the compressor shuts off. Steve has had to replace ours several times.
ETA RAP6354 is the HWH part number. Typically around $90-150 depending on who you buy it from.
Here is post showing pic HWH Compressor Fix (http://www.foreforums.com/index.php?topic=9936.msg110381#msg110381)
Also, note that the bowl sometimes cracks at the fitting that the purge valve is screwed into. We had to replace ours in 2011. RAP90539. Here is a post with a pic of the box showing OEM info HWH Parker Compressed air filter replacement (http://www.foreforums.com/index.php?topic=21886.msg164287#msg164287)
Carol- sorry to hear about your troubles with your HWH system. I just left there today-they are great people to work with and should be able to help you solve your issue.
Ask for a complete check of your system while you are there. When they checked mine- they identified and marked 7 air leaks in my air system that are not part of the HWH system. Now I have other things to get replaced..............oh well, my HWH is working well.
Your system will work well when you leave them also.
Safe travels to you and Jeff.