REPLACING AUX AIR PESSURE SWITCH ... HELP.

[CCMH]

Morning all, All thumbs repair man here. ;)

Well, am going "face in" at my FIRST Air system repair today, (hard to admit), and was wondering if someone who has done this before might be willing to walk me through the process step by step. I picked up a new Square D pressure switch today, identical to the one in my coach, and am going to attempt to install it myself. Have posted pics of the old one, and the new one.

The old valve is leaking air as it airs UP the aux system. It eventually gets to 120 psi, but deffinately takes its sweet time. Once it shuts off, it holds for about 2 hours. While I understand that there may be leaks elsewhere as well causing this, I thought I would start here as there is considerable corrosion on the old release valve (the source of the air up leak).

Thanks all..... kind of my maiden voyage into my air systems.

If I can fend off Christine for a moment as she politely, and lovingly, but oh so insistantly says "Shouldnt a professional be attending to this?" I might just be ably to fix it! Or not... then I will have to watch her smirk when I attempt to fix things on the bus. Don't get me wrong.... she is a REALLY HOT WOMAN, and I LOVE to look at her. The smirk? Not so much. :-)

Thanks for your help everyone, or anyone.

[michaeldterry]

Have posted pics of the old one, and the new one.

..snip...

Don't get me wrong.... she is a REALLY HOT WOMAN, and I LOVE to look at her. The smirk? Not so much. :-)

Thanks for your help everyone, or anyone.

Curtis - forget the pictures of the switches - let's see some pictures of Christine! :p :D

[Richard Barnes]

Curtis,

We'll learn together. I've got the identical problem and will pick up my replacement switch at Grainger this afternoon. I want to add a guage as well so if anyone has any advice I'd appreciate it as well.

[CCMH]

Richard,

Glad I wont be doing this alone! :) I might even let Michael take a peek at Christine's smirk, if I can get someone to help me with this! Got my part at grainger as well. Fill me in if you get any further info on this.

Curtis

[Jon Wehrenberg]

First of all guys the switch on my coach, and likely others handles 120V so step #1 is to make sure the power to the aux compressor and the switch is OFF. Please do whatever it takes on your coach to turn it off and then double check to verify it is off.

I have replaced a couple of these switches and if it is like mine (looks the same) you have two wires to disconnect and reconnect and an air fitting to remove and install.

For the replacement ignore any switch adjustment until you know how it is set by running it when you are done. If you do not have a pressure gauge now is a good time to install one so you can see the pressure cut in and the cut out pressure. To install a pressure gauge put a "tee" in the line anywhere and thread the gauge into the "tee".

Make sure you use thread dope or teflon tape to get an air tight seal at any air connections. If you need specific info post pictures of your questions and I in turn will take pictures of my installation so we will be better able to communicate.

[CCMH]

Thanks Jon,

Questions about air preparation:

Should I relase all the air from the release valve under the driver bay first, or release from driver bay AND rear release from right hand side of rear of coach as well before starting procedure? How should the coach be sitting before I do this? Do I need to adjust the level low system before? Or should there be no need to realease air at all? etc...

Curtis

[Richard Barnes]

Thanks Jon, the electrical connection was my first thought. I have a dedicated breaker on the main panel but I'll double check that the power is off. I bought the tee connection for the guage and will install it as well. Thanks for the help.

[Jon Wehrenberg]

Curtis,

The pressure switch has auxiliary air pressure on it only. It is only air so you don't have to worry about bleeding it since it will escape when you loosen it. Your coach will not settle as air in the aux system is lost, but just keep your knees out from under it anyway while you are working on it. With the key off your air bags should have the air "locked" in them and aux air pressure (or lack thereof) will have no affect on them. In fact, with no air pressure in the aux system it should be impossible for anything other than a leak in the air bags or related fittings and valves to enable air to escape from them because air pressure is required to open the valves.

Also as the aix air is bleeding off, take the opportunity to go up and look at the dash air gauges. They should not move as air bleeds off. If they do move it indicates a defective protection valve that you might want to get replaced. Anytime I work on my coach I look beyond what I am working on to check out other things that I might not ordinarily be looking at.

[BenC]

First of all, the aux compressor on a Vantare (unless retrofitted with a different one) is 120vac, but Vantare utilized a 12vdc circuit to control a relay, so there is no high voltage potential at the pressure switch. The fuse for the control circuit is located in the closet with all of your other 12v distribution circuit fuses, and there should be a label telling you which position the fuse is in to remove it. If you remove the fuse, you won't have to worry about shorting out the wire during or after removal from the screw terminal on the pressure switch and blowing the fuse. Vantare ties into the Prevost Aux Air system in several places, so there is no easy way to disconnect the air source from the Prevost and leaving it pressurized and the Vantare system vented. The leveling system should not let suspension air back out if none of the valves are leaking. Neither should the Primary or Secondary Brake tank air be released if the check valves are working properly and not letter air bleed out back into the aux system. Venting the aux tank locally should remove the air pressure allowing you to remove and reinstall your pressure switch. Of course, the Prevost maintenance manual, to cover any situation, tells you to not only completely vent all air tanks, but also to remove the battery cables...a bit of overkill. There is what people tell you "officially" to CYOA, and then there is reasonable advice. Proceed at your comfort level. Don't be afraid to consult your Prevost Maintenance Manual. There is a wealth of information in it. Since Vantare basically tied right in with the Prevost Aux air system, the information Prevost supplied about discharging air from the system will apply to the entire auxiliary system. Essentially, the moisture separator in the front steering compartment is what I would use to discharge the compressed air from the system. Then to ensure you keep the system discharged in the event of Brake System check valve leakby or Norgren leveling/suspension valve leakby, leave the moisture separator vent cock open the entire time and you will ensure the system is bled down. Of course, make sure you close it before restarting the compressor and attempting to pressurize the system. Hope that helps.

Ben
Coach Worx

[CCMH]

Great guys! THANKS!!! Am going to tackle this first thing in the morning, and will keep you posted as to the results.

Jon, you are ALWAYS a cornucopia of information, and I for one am extremely grateful for your pressence on and in this forum. Thank you so much for your selfless willingness to take the time to help us with issues that probably make most of us want to hurl! :)

Ben... you have just established a new customer, and am looking forward to meeting you in February when I am planning on bringing my coach to you for a deep look over. Your knowledge of Vantare Featherlite coaches is impressive, and very valuable to me. Look forward to meeting you and THANKS!

[truk4u]

Now would be a good time to add an aux pressure gauge and be able to keep an eye on what the aux system is doing while driving or parked. Here's a link to my gauge installation:

http://forum.prevostownersgroup.com/showthread.php?3914-Digital-Aux-Air-Pressure-Gauge&highlight=gauge

[Jon Wehrenberg]

Just to add to Ben's advice, Richard's switch has 120V. Be careful Richard. I believe you are correct in that the aux compressor switch in the panel should kill all power to the switch, but still test it to be sure.

[CCMH]

All done! Working like a champ now holding pressure at 125psi. Took me about 15 minutes, and a $31.00 part. Best part is Christine's smurk turned into a smile. :)
How you fairing on yours Richard?

[BenC]

Thank you. I look forward to meeting you in February. Don't forget that if you get in a bind about anything in the meantime, you can always call me either here at work or my cell. I will answer unless I'm asleep lol. 8138308619. Happy Holidays.
Ben @ Coach Worx.