air bags will not inflate

lajuene · 04-29-2012, 11:08 AM

I think my HWH ststem is not passing the signal to the air valve solenoid to inflate the airbags after the jacks are retracted and stored. That seems to be the concensus of my RV service dealer and Freightliner.

I need to inflate the bags to drive it to the service center. Freightliner has told me I can manually fill the bags by pressing a button on the solenoid under the coach. There are 2 solenoids, one dumps the air and one adds the air. Glenn at Freightliner explained the process and described the area but I was wondering if someone has taken photos that might show the solenoids so I can find them easier. (if I can get under the coach while it is in the down position)

I'm also posting this to the Freightliner forum.

Going to try to do this later this afternoon. Photos would sure help.

Thanks
Eric

cbeierl · 04-29-2012, 11:50 AM

My understanding is that the bags should also inflate if you put it in gear (though I haven't tested this). I don't know if the HWH system controls that as well, but it might be worth a try and see if anything happens.

troth · 05-01-2012, 10:04 AM

HWH makes a good reference manual all about how the combined air bag system and HWH hydraulic levelers should work. You can get it online: just google "air bags and HWH jacks".

cbeierl · 05-01-2012, 11:24 AM

Here's a link: Air Suspensions and HWH

I believe that we have the pilot air dump system.

lajuene · 05-01-2012, 04:13 PM

Thanks for the link. As it turned out... The service center sent a mobil mechanic to get the air bags up and showed me where the button on the solenoids were under the coach. They thought it would be a bad HWH but they re-zeroed the HWH, whatever that means, and now it works fine. Cost me $400 bucks for labor including the expensive mobil visit. Coachnet covered $125 so that was good. Not really sure what the problem was. I suspect it was a sticky valve or solenoid that is now ok. Next time I'll know where the button is under the coach. Freightliner tried to describe where it was but I spent a half hour under there and could not find it... now I know

the4js · 05-02-2012, 02:03 AM

Mine did the same thing once. I drove it with no air in the bags and just about bounced my teeth out. turns out when I hit the dump botton i didnt hold it long enough. Once I drained the air, it filled back up no problem.

lajuene · 05-05-2012, 09:42 AM

Photos are here:
lajuene Gallery - iRV2.com RV Photo Gallery

lajuene · 05-05-2012, 09:49 AM

It appears that I used my leveling system using the wrong sequence. HWH says to have engine off and key on or in accessory position THEN press DUMP or LEVEL button (depending on which system you have. I had the engine running when I leveled, dumped, put jacks down. The engine is then trying to air up bags as HWH is trying to dump bags. Apparently this may have caused the system to glitch and caused my problem. Manually airing up the bags was probably all that was needed. The additional labor for Alpin Haus to tinker was probably not needed. They said they "Re-zeroed" the HWH system and then it worked fine. Don't think I buy that but who knows. I now know how to do it myself so it was tuition, not a repair bill.

Let me know if there are questions about the photos.

bachler · 05-05-2012, 10:20 AM

Ours Done that several times. What I started doing was to start the engine and let it idel for a few minutes, BEFORE i retracted the Jacks. It seems When I Retracted the Jacks first It would take 10 to 15 minutes to get the Proper air in the system.. Inflate the bags first then Raise the jacks..

bonzocfi · 05-05-2012, 10:25 AM

Here's a trick I learned from Spartan. If your air bags fail to inflate after jack retraction, release the parking brake, pump the brakes a couple of times the set the parking brake. Do this twice. This should force enough air to open up the stuck solenoid. Works for me every time!

cbeierl · 05-05-2012, 10:47 AM

Quote:

Originally Posted by lajuene

It appears that I used my leveling system using the wrong sequence. HWH says to have engine off and key on or in accessory position THEN press DUMP or LEVEL button (depending on which system you have. I had the engine running when I leveled, dumped, put jacks down. The engine is then trying to air up bags as HWH is trying to dump bags. Apparently this may have caused the system to glitch and caused my problem. Manually airing up the bags was probably all that was needed. The additional labor for Alpin Haus to tinker was probably not needed. They said they "Re-zeroed" the HWH system and then it worked fine. Don't think I buy that but who knows. I now know how to do it myself so it was tuition, not a repair bill.

Let me know if there are questions about the photos.

If you read the linked HWH document (above) which describes how the system works you'll see that with a pilot air dump system (chassis supplied, which I'm certain we both have) it shouldn't operate that way. I dump/level my coach all of the time with the engine running without a problem.

YC1 · 05-05-2012, 11:07 AM

Not the exact system but my dad had an issue while traveling when his bags went down. He pulled over, raised the rv with the jacks as high as it would go and the bags filled enough to let him go another 30 miles or so before repeating the process.

lajuene · 05-05-2012, 11:14 AM

Actually the above HWH manual says to have engine off when dumping. My system is manual and a model 325. Other systems may very well work differently. I'll look it over again. The manual talks about many differnet systems and maybe the one you read is a different one?

lajuene · 05-05-2012, 11:19 AM

"One of the important rules to follow when using an HWH air dump system is the vehicle engine
must be off. If the vehicle engine is allow to run while dumping air and leveling the vehicle, the vehicle air
supply will not dump properly." page 2

lajuene · 05-05-2012, 11:23 AM

"An advantage of using a pilot dump system is that the dump valve isolates the air bag from the height
control valve while dumping the air from the air bags. Air is not dumped from the main air supply and the
vehicle engine can be run during a leveling procedure. Another advantage is the pilot dump valve stays in
the position it is shifted to. This means there should be no problem with air seeping into the air bags after
the leveling procedure is finished. BUT, this can also be a disadvantage if there is a system failure. If a
failure causes the pilot valve to not shift into the travel position, the vehicle cannot return to ride height. " page 5

This explains my confusion..... it seems to contradict itself until I read it closer. I think my pilot dump valve stuck. The tech did have to pull one of the buttons out with needle-nose so.....

Thanks for all the ideas and discussion. I think I'll be ok now if it happens again. I understand the system MUCH better now.

EngineerMike · 05-05-2012, 11:27 AM

I'm thinking Chris is right and this may be a recurring issue. Sounds to me like the Pilot Dump Valve assembly is sticking or a control feature is not controlling, and needs some manual tickling. Usually that means an eventual rebuild or replacement of a part. The referenced HWH doc has enough info to allow troubleshooting. Thanks for the link.
If you do any user servicing and open the gizmo up, use a very light coating of silicon type lube on reassembly (SuperLube brand is available at most home and many auto parts stores).

cbeierl · 05-05-2012, 11:35 AM

Quote:

Originally Posted by lajuene

"One of the important rules to follow when using an HWH air dump system is the vehicle engine
must be off. If the vehicle engine is allow to run while dumping air and leveling the vehicle, the vehicle air
supply will not dump properly." page 2

They talk about two different systems, the "HWH air dump system" (supplied by HWH) and the "pilot dump system" (supplied by the chassis manufacturer).

We both have the pilot dump system on our Evolution chassis. Read section 2-3 (on page 4) of the HWH doc. You'll notice that the illustration of the pilot dump valve matches your pictures from under your coach.

lajuene · 05-10-2012, 11:37 AM

I'll get it. Still have to push that button to air up after jack use but I'm going to try to lube it a bit. surface corrosion may be just causeing the button to stick. I barely touched it and it started airing up.

lajuene · 05-10-2012, 12:09 PM

I just wanted to re-post my wire photo. I thought it would be easier to see if it was here instead of my photo gallery.

lajuene · 05-19-2012, 08:56 AM

Quote:

Originally Posted by lajuene

I just wanted to re-post my wire photo. I thought it would be easier to see if it was here instead of my photo gallery.

this post was placed here by mistake, it belongs on my Invisibrake thread. sorry. Don't know how to delete it but I'll try to figure that out.