[bikestuff]

Gang,

A while ago I noticed that if I turn my 120V air compressor off, the front two slide seals will leak down and be flat by the next morning.  The two rear seals stay inflated.

I thought the 12V compressor would work the air door, the toilet, and the slide seals.

Upon discussions with Newell...They said that the seals only work off of the 120V and that what I am seeing is normal.  The 12V compressor only provides air to doors and toilet.

Could this be right????!!!   If this is correct, everything that I thought I knew about our air systems is wrong!

So what I am gathering is that the engine air and the 120V can feed the tank that supplies the door and toilet.  But the 12V does not provide air to the tank that feeds the slide seals.

Please set me straight!

Cheers,
bill

ps.  the reason that the real seals stay inflated is that they don't have any leaks...but apparently there are small leaks in the front two seals.

[folivier]

Interesting Bill. Perhaps the single 12v air compressor is too small to supply 4 slide seals? Is it a problem, IOW do you dry camp often? If so you may be able to add a 2nd 12v AC to supply just the slide seals?

[Richard]

I would put this in the category of no two are alike. I am guessing that Newell made changes in the logic from model to model. Taken to modern day where there are two 120AC compressors.

[bikestuff]

It's actually not much of a problem but it is important to realize that if the 120V compressor fails, then rain, bugs, varmints of all sorts can get into the coach....I would rather use the 120V and then have the 12V as backup...similarly to the way that the water pumps work.

[rheavn]

Bill,
I do believe that once the coaches went to four slides Newell found that the 12V pump would not keep up.  They kept the 12V air pump for awhile to service the inner air doors and the toilets.  Even that became too much for the 12V air pump when they changed toilet brands.  Then they went to just the 120V air pump.  Now they have two 120V air pumps on the coaches.

[bikestuff]

Newell rebuilt the check valves on the front slides today. Right now I am running a test with the 120V compressor off, and the air dumped from the front tank. We are looking to see how long the seals will stay inflated. (The same test before working on the check valves showed that the front two seals went completely down overnight).

If the seals will stay inflated for days/weeks with the 120V supply off, I will be less worried.

I really liked Forests suggestion of an aux pump. I may start thinking along those lines. (Newell suggested plumbing in my pancake air compressor, but that seems a little bulky/clunky to me).

[bikestuff]

The result of the check valve fix was that one of the seals now stays well inflated but the other (Slide 1) deflates overnight. I am thinking that I have a slight leak somewhere in the slide seal.

So....Just to wrap this up.

The seals are fed from the 120V compressor and tank only. The 12V compressor and tank are not associated with the seals.

If you turn off your 120V compressor, you WILL eventually lose pressure in your slide seals.

I am not satisfied with this answer and will continue to search for a viable alternative.

[77newell]

Question (my engineering mind is curious - I don't have slides) : Unless the rubber of the seals is somewhat porous I don't understand why these systems are so prone to leaking down. Given that one of the slide's seals stays inflated I doubt the seals are a problem other than when they have a pinhole or other puncture. The rest of the system is "just" mechanical and should not be leaking at all (again my engineering mind of perfection).

Usage of air for doors and toilets is reasonable. Adding compressors to deal with leaks would bother me. I would rather hunt down the leaks and keep the system as simple as possible (KISS - another engineering concept that can cause me to spend way too much time under my coach). One of the difficulties we have in dealing with these complex air systems is the lack of a comprehensive system schematic. Trying to figure out how the system is configured while trying to solve a problem is really time consuming. I use the hand drawn schematics of parts of my 93 coach's air system regularly when air consumption rises, it took many hours to put together but has saved me lots of time in locating leaks. I went from the 120v compressor running at least a couple times an hour to twice a day by persistently chasing down leaks. I will consider my efforts a success only when the compressor never needs to run unless I use the air doors (I think that is called compulsive mental illness, or is it obsessive mental illness, probably both).

Perhaps at this summer's Guru gathering a joint effort could produce a series of schematics showing the evolution of the air system. Those would be really useful for troubleshooting leaks. I would be glad to help with that if I'm there, but I'm helping a son make a move cross-country and don't yet know the schedule of his need for me.

[ccjohnson]

Feel free to run down air leaks on our coach at the rally!