[DON]

Numerous made by the various manufacturers…. If you want to learn A LOT, do a search from the main search function for LoneStarAce. He also has a detailed post with photos addressing this exact issue.

After my Liberty Coach installed Parker brand water filter located inline after my aux air compressor, I added a coalescing filter to ensure the driest possible air.

Install any filter as far away from the compressor as reasonably possible as want the air to cool for best moisture removal.

[Andrew]

Downstream of the MP100 California Air Tools 120vac aux compressor I installed are 2 SMC brand, Model AMG 150C-N02, air water separators with auto drains.

Liberty had installed 1 of them, I installed the second one.

[Jeff]

Don, Where is your California air tools 120 volt located? Do you have an off/on switch on the dash panel ? Where is your 120 volt receptacle located? Thanks, Darrell

[Archived]

It seems I have some form of one in my air stack, just need to investigate further.

Is there a pressure switch/relay for a compressor already installed somewhere? I bought one just hoping I don’t need to install it. I think it’s a 90/120. It’s like 5 degrees out this week so haven’t spent more than a couple minutes to look.

[Jon]

In May of 2014 I removed the failing Gast brand 120v aux compressor and installed the California Air Tools MP100 – $200.

Liberty installation of the Gast aux compressor was in the nose, behind the bumper, centered in the back behind the CruiseAirs. Accessed from underneath the bus, just forward of the solid axle , there’s a removeable panel. I installed the C A T MP100 in the same place, but I did build another box for it to live in.

There is a Pumptrol brand 120vac adjustable pressure on/off switch. Remove the gray cover and you’ll see the nut/spring for adjustment

There is also a 120vac Versa brand normally closed valve/solenoid to shut the air supply off. You can see the Versa between the air/water separators and gray Pumptrol switch.

You can see my aux comp box in the back with its capacitor on it.(last pic)

Your results may vary 🙂

/threaddetails.asp?Category=&ThreadID=6168

and

/threaddetails.asp?Category=Pneumatic%3E&ThreadID=8748

[Archived]

Every owner needs to understand how aux air enters their coach pneumatic system, and then recognize the moisture introduced by the aux compressor is trapped or collected.

The worst thing that can happen to a pneumatic system is to allow moisture to enter it. But if it does the potential damage can be mitigated by draining it. For a great number of owners doing so is not as simple as I made it sound.

Start by making sure the air dryer installed by Prevost is serviced regularly, and that anytime someone is under the bus all of the air tanks are drained in sequence, not only to drain moisture, but as a means of checking the integrity of the various valves within the pneumatic system, especially the brake system.

Usually a converter installed aux compressor that does not have an air dryer or moisture trap will deliver moisture to the accessory tank. Whatever type of device is used to trap aux compressor moisture, it needs to be drained or serviced regularly.

If dryers or traps are used and maintained, every time the tanks are drained of air not a drop of moisture will ever be seen. To appreciate how important that is imagine how moisture creates corrosion and then imagine what it will cost to replace all the Norgren valves, protection valves, and any other component with steel or raw aluminum exposed to that moisture.

On my coach I can trap around a cup of moisture per week when in a humid environment if the aux compressor is cycling often, such as for pocket doors and other air usage.

[Jeff]

Here’s what mine looks like. Hopefully it works up more tomorrow so I can spend a few more minutes and clean up any wiring. I pulled the Prevost schematics off their site but was seemed even more complicated.

The stainless steel braided line is my new compressor that just fit in the spare slot that has a converter tag. I don’t think is the right spot though, looks after everything. Am I right to assume that bottom right thing is a dryer? The valid slide components aren’t visible.

There was a pair of wires labeled air compressor and i see a small air hose that goes into my 2nd bay which looks like someone ripped out the compressor before selling. Was hoping to find a regulator pre-installed. The air hose seems a lot smaller than my new compressor.

Also the Viair regulator screw seems smaller than the air compressor regulator. Guess I’ll have to run to the store and get a tee and put them all together.

Trying not to touch too much as one noregen valve I touched last time crumbled and had to replace. Still have a few small leaks

[jackie]

Yes, bottom right thing is a Norgren air/water/separator filter.

Mine had one and it never had water in it. I replaced it with a WIX AquaChek ACK10.

/threaddetails.asp?Category=Pneumatic%3E&ThreadID=11677#90611

[Jeff]

Thank you. After looking at the schematics (which are very confusing) It seems the air comes in from the Bendix compressor to the Haldex dryer to the wet tank to the secondary, primary and accessory tanks. From the accessory tank right into that air/water filter. There’s also a valve on the inbound part of the filter, so I plan on adding a T (or 2) and putting the air compressor and the pressure switch there, while keeping that valve. I believe that valve has a shrader valve like a tire to fillup incase of issues.

Do you know if this will fill my accessory tank or is there a checkvalve somewhere blocking it? Also how do the other tanks operate? I believe they open at 90psi so if my compressor is pumping 100psi it should fill all the tanks and bags right? I want my bags to be full so I don’t lose level overnight if any leaks. I want to get the aux air system figured out before I start tracing leaks and replacing bags so I know what to expect.

https://techpub.prevostcar.com/en/pneumatic-diagrams/search-pages?filters%5Bcode%5D=D140302&filters%5Bsearch_units%5D=5-8560&filters%5Bsearch_serial%5D=

[Archived]

The engine driven compressor adds air to the system from the dryer to the wet tank, rear tank, front tank, and when the pressure is about 70 or 80 the protection valve allows air to enter the accessory tank.

Draining the entire system regularly is not only a way to insure moisture is removed, if it is done in sequence, starting with the wet tank if verifies all the valves are functioning. When airing up the chassis system the primary and secondary air tanks will reach 70 or 89 PSI before passing air into the accessory tank.

On the house side, an aux compressor should feed into the accessory tank directly, through a dryer or water separator. As long as the system was checked as described above aux compressor air pressure will be limited to the accessory tank and will not move past the tank to the others. If it does it is likely a failed protection valve or check valve.

If there is an inadequate dryer or water separator moisture will be fed into the accessory tank and problems will ensue.

[Archived]

Thanks Jon, So is the airbags on the accessory tank? It appears so on the schematics. I’m not certain what S and D means or where the check valves are.

Interesting how the secondary and accessory tanks are next to eachother and connected. I’m assuming the check valve is somewhere in there then.

[Art]

Yes – all airbags (genset also) use accessory air.

S = supply

D = delivery

Check valve for primary tank is affixed to / threaded into the tank. Same for secondary tank. None for accessory (aux) tank

[Jon]

Pri & Sec brakes (brake tanks) take priority over suspension etc (aux tank), so there is a Bendix 75 psi PR-2 pressure protection valve, pt # 277227N, before the aux tank forcing the engine driven compressor to fill the primary & secondary brake tanks to 75 psi first. Then the PR-2 valve (see pic) opens and allows air to the aux tank (suspension etc).

A lot of our Prevost didn’t come equipped with aux gauges, so you don’t know whats up with the suspension etc.

I added 2 gauges: /threaddetails.asp?Category=Pneumatic%3E&ThreadID=6196#57135

Our Prevost have a lot of Bendix parts. Here’s a catalog of them: https://www.wanderlodgeownersgroup.com/downloads/BENDIX%20QUICK%20REFERENCE%20CATALOG.pdf

[Archived]

Thanks so much!! Mine has aux gauge on dash