Can the Air Compressor be Isolated and Shut Down?

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Can the Air Compressor be Isolated and Shut Down?

October 25, 2016, 02:22:13 pm

Howdy folks,

I apparently have a developing minor, but steadily worsening, air leak. No obvious indications of what is leaking, but the compressor is running with shorter and shorter down times. Presently cycling on about every minute and a half to three minutes.

We have the coach plugged in to 50 amp in the driveway right now (not on auto-level), but will be moving it over to the storage lot in the next few days. Am trying to stall long enough to wait until our service visit to MOT in December to get this found and repaired. All slideouts work without problem.

I am concerned about the amount of time the compressor is running. Can this be safely isolated and turned off while the coach is parked? If so, am somewhat curious about the ramifications of this. Might be able to show what is leaking (i.e., imbalance due to air bags leaking), but might not be a good idea for reasons I am not considering.

Any thoughts or inputs?

As always, thanks!

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #1 – October 25, 2016, 05:22:37 pm

Hey Don,
It is not a good idea to,let the air compressor run ll the time. You need to understand wphow yours is wired in order to shut it off. The pressure switch supplies power to the compressor and it may also energize a solenoid or other things. These got more complicated over time. Power to the compressor or to the pressure switch can be interrupted with an inline fuse that gets pulled or a switch to disable it or a relay powered by a remote switch to cut power. Where you put these depends on how yours is wired up.

I added a switch up front to turn off the compressor if I do not want it on.

My coach will stay level within my tolerances for a week or more at a time with the level system off and the compressor off. Your leak seems significant. It needs attention.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #2 – October 25, 2016, 05:46:52 pm

I assume the compressor you are referring to is the one used to provide air pressure when your main engine is not running (i.e. driving). I see two issues you need to be concerned about, one is uneven air pressure in air bags, two, is lack of seal around the slides with no air pressure (particularly if stored outside). I do not have air bags so cannot comment about the risk with no slide seals. For air bags, if you loose pressure in one corner it will sag and put a twist on frame which can pop the windshield out or crack it in one corner. If you dump all the air with the HWH control so your coach settles onto the rubber bumpers inside the air bags you will mitigate the risk of cracking the windshield. I have been told by a Foretravel owner that it is not recommended to dump the air bags, however, I do it all the time and my coach sits on the rubber bumpers inside the air bags for weeks at a time without problems.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #3 – October 25, 2016, 06:56:19 pm

I had similar symptoms on my 2002 U295. Ended up replacing all 8 airbags. Great improvement. Just another consideration

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #4 – October 26, 2016, 12:50:18 pm

Well, I have an update for anyone encountering this type of issue. You never know when someone else might have a similar problem.

The leak gradually worsened, to the point the compressor rarely would cut off. Got in touch with MOT and spoke to their newest senior support specialist, Aubrey Lee. "Newest" is somewhat misleading, as Aubrey comes from almost 40 years experience with Foretravel.

With Aubrey's very patient and extensive advice, we were able to narrow this down to the two passenger side manifolds in the electronic bay. Those are the two manifolds at the top in the attached picture.

The actual leak is right behind the two shutoff valves below the manifolds. Those shutoffs are the black (and grey, on the left) handles you see right below the manifolds. The cylindrical brass valve they sit on is a check valve. This is what needs to be replaced.

So, I've ordered two check valves and with, I am sure, more handholding from Aubrey I will attempt to replace these. Not something I can hold off doing until they get the coach in December for our annual maintenance.

I'll do what I hope will be a final update once I have received and installed the valves.

As always, thanks for all the suggestions and pointers.

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #5 – October 26, 2016, 01:12:47 pm

Slide manifolds?

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #6 – October 26, 2016, 04:01:12 pm

While you are waiting for the parts you should be able to disable the 12 volt compressor by pulling the fuse. In my case that fuse is located very close to the compressor. With that fuse pulled and the HWH autoleveling disabled by pushing Emergency Stop while the ignition key is ON I don't think it will run.
Just occasionally check the slide seals the be sure they remain inflated.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #7 – October 26, 2016, 06:12:17 pm

Quote from: Don Rickey – October 26, 2016, 12:50:18 pm

So, I've ordered two check valves and with, I am sure, more handholding from Aubrey I will attempt to replace these. Not something I can hold off doing until they get the coach in December for our annual maintenance.

Don,

Glad it was something simple! And good info to hear Aubrey is at MOT. He's a great technical resource.

Lots of us have replaced those slide manifold valves with 1/4 turn ball valves from the air compressor department of Lowes or Home Depot. Much more robust. Emergency '03 slide bladder repair

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #8 – October 26, 2016, 10:05:30 pm

Quote from: Dick S – October 26, 2016, 04:01:12 pm

While you are waiting for the parts you should be able to disable the 12 volt compressor by pulling the fuse.

Good tip. I was able to locate the fuse and disconnect so that the compressor would not burn itself up! Keeping a close eye on the slideouts and airbags. So far, so good.

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #9 – October 26, 2016, 10:07:56 pm

Quote from: Michelle – October 26, 2016, 06:12:17 pm

Lots of us have replaced those slide manifold valves with 1/4 turn ball valves

Michelle,

Thanks for this info. I looked at the article and I am almost certain that nailed down what I was feeling. All of the leak was coming from behind the stem, just like Barry referenced. I did not understand how it was constructed, but his article clearly explained that.

Many thanks!

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #10 – November 03, 2016, 03:34:57 pm

Final update to close this out for anyone experiencing similar problem.

Got the replacement valves in from MOT and installed them. These were for the two slideout manifolds servicing the passenger side. Waited two days to be sure the thread sealant (RectorSeal No. 5) had adequate time to set up and then fired up the compressor. Worked great. Ran for about 4-5 minutes to refill the small tank, shut right off and stayed off. No leak at all from behind the valves now.

Ran into a little side issue that merits mentioning. I regularly bleed all four air lines to make sure they stay dry. Thought it would be a good idea after this service and that turned out to be the right thing. Three of the lines were nice and clean and dry. The fourth line, which directly feeds from the small compressor to the small air tank up front, was full of water. Must have got at least a pint, maybe a quart, out of it. Really startled me. Took a closer look at what appeared to be an overflow reservoir attached to the side of the compressor and it seemed to be full of water. Hadn't noted that before.

Contacted Aubrey at MOT and he confirmed this was the purpose of that reservoir. Had me go ahead and drain it from the valve at the bottom. He said the presence of this much water in the compressor line was not surprising, given the humidity here in Virginia coupled with the extreme amount of time the compressor had been running to keep up with the leak. I'm going to keep clearing this line over the next few days to make sure I get all the moisture out. Still getting a heavy mist from this line at this point.

Many thanks to all who provided information on this issue. I have a PM into Barry to ask about what is involved in changing these factory valves over to the ball valves people get from the local hardware store (thanks Michelle for that tip). Absent that info, I plan to have MOT replace the other two valves for the driver side slideout manifolds when we do our service call in December.

An early wish for a safe and happy Thanksgiving to everyone here!

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #11 – November 03, 2016, 04:25:44 pm

Hey Don -

Re: Overflow reservoir / water trap

I may not be understanding what you are saying and your setup might be different from ours, 2007 vs 2002, but on the bottom of that clear bowl / water trap that is catching the water, we have a solenoid that opens when the Aux. Comp. turns off and blows any water/moisture in the bowl out. Ours also has some desiccant material in it that absorbs moisture. Blue is dry/good, Pink is wet/bad (needs to be replaced).

See attached doc.

Sorry if I am being redundant or misunderstand.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #12 – November 03, 2016, 04:38:56 pm

Quote from: Don Rickey – November 03, 2016, 03:34:57 pm

Ran into a little side issue that merits mentioning. I regularly bleed all four air lines to make sure they stay dry. Thought it would be a good idea after this service and that turned out to be the right thing. Three of the lines were nice and clean and dry. The fourth line, which directly feeds from the small compressor to the small air tank up front, was full of water. Must have got at least a pint, maybe a quart, out of it. Really startled me. Took a closer look at what appeared to be an overflow reservoir attached to the side of the compressor and it seemed to be full of water. Hadn't noted that before.

Contacted Aubrey at MOT and he confirmed this was the purpose of that reservoir. Had me go ahead and drain it from the valve at the bottom. He said the presence of this much water in the compressor line was not surprising, given the humidity here in Virginia coupled with the extreme amount of time the compressor had been running to keep up with the leak. I'm going to keep clearing this line over the next few days to make sure I get all the moisture out. Still getting a heavy mist from this line at this point.

Don, can you confirm that in your '07, FT eliminated the desiccant bowl for the aux compressor? I know they had eliminated it at some point after 2003, and it will help the forum (and folks responding to questions like this in the future) to know what years have and do not have the desiccant bowl.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #13 – November 03, 2016, 05:57:21 pm

These last two points are good.

It looks to me like it does have that desiccant bowl, but I am not sure. I'm going to try and attach a pic. If it is and mine has a solenoid that "opens when the Aux. Comp. turns off and blows any water/moisture in the bowl out", it is not working. I just unscrewed the cap at the bottom and emptied the bowl.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #14 – November 03, 2016, 06:19:14 pm

Quote from: Don Rickey – November 03, 2016, 05:57:21 pm

These last two points are good.

It looks to me like it does have that desiccant bowl, but I am not sure. I'm going to try and attach a pic. If it is and mine has a solenoid that "opens when the Aux. Comp. turns off and blows any water/moisture in the bowl out", it is not working. I just unscrewed the cap at the bottom and emptied the bowl.

On the older systems, the desiccant bowl is an additional bowl with a "cage" covering it and labels telling you about the indicator color of the desiccant media/beads inside. The bowl you show doesn't have a solenoid on it (it would be where that bottom cap is), but appears to be similar the condensate bowl that in an older system would have a normally-open solenoid tied to the aux compressor power (so it would close when the pump runs and open when it shuts off to expel the condensation).

It looks like the elimination of desiccant may have been as early as 2007, if you don't have that second, caged, bowl.

Do you have your owner's manual for the coach? If so, can you check it to see if there is any information on how often you should look at and empty that bowl?

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #15 – November 03, 2016, 07:18:53 pm

In the photo above, the white air line goes to the bowl with the pop off valve. The black air line going to the bowl in the photo comes from the desiccant bowl. I suspect that the reason the bowl in the photo is full of water is because the desiccant in the desiccant bowl has not been serviced (changed).
Larry

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #16 – November 03, 2016, 10:05:17 pm

Larry,

Given your information, I have a hunch my ignorance is on display here again.

I'm going out tomorrow in the daylight and trace the white and black lines to see if I can detect the bowl with the pop-off valve and the desiccant bowl. If there is an desiccant media, I can confirmed it has never been serviced. I'll correct that right away.

I'll post again after I look at this more closely.

Thanks everybody!

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #17 – November 04, 2016, 09:33:29 am

erroneous information deleted - sorry about that!

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #18 – November 04, 2016, 09:55:08 am

If Don's coach is as it came from Foretravel, there are three bowls. The first bowl has the solenoid, the second bowl has the desiccant, and the third bowl is the one in his photo. Go to MOT's website and look at the photo on one of the 2007 Nimbus's for sale to see what I am saying. It is just like it was on our prior 2004.
Michele, the black air line in your photo goes to the bowl in Don's photo.
Larry

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #19 – November 04, 2016, 01:47:04 pm

OK, I think I am narrowing this down thanks again to everyone's help.

It appears that I have exactly what Larry described and Michelle referenced. I have posted three additional pics. One showing all three bowls, one closeup of the bowl with the solenoid (my finger points to the waterline) and one closeup of the desiccant bowl. The color of the desiccant is pretty dark and I am sure well beyond need of replacement. Going to add that to my work order.

Michelle, I don't think the solenoid was malfunctioning or the source of the excessive run-time of the compressor. That appears to have been caused by the two leaks I eliminated by replacing the manifold valves. However, I'll certainly be running that by MOT at my service appointment.

I'm assuming there is nothing I can or should do about the water in the solenoid bowl. It's close to full, but maybe that is the way it is supposed to be. Kind of concerns me if it is designed to expel water into this electronics bay.

I'm beginning to think I may have to abandon my Brett Wolfe wannabe goal. Gonna have to be more realistic. Now, if I can just find my community college handbook and see when they are offering those rocket science courses.

Don

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #20 – November 04, 2016, 02:45:30 pm

Can't tell for sure from the picture, but looks like someone put a plug in the solenoid valve to keep it from leaking out air when the compressor is on. There should be no water in that bowl as it has a normally open solenoid valve and only closed when the compressor is on and when the compressor shuts off the valve opens and expels the water in the bowl. Not a big deal as very little water comes out during normal operation.

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #21 – November 04, 2016, 05:50:47 pm

Quote from: ltg – November 04, 2016, 09:55:08 am

If Don's coach is as it came from Foretravel, there are three bowls.

Larry, you are correct. My error. It's been a while since I had my head in that bay, and I checked and confirmed your correction. Thanks!

Re: Can the Air Compressor be Isolated and Shut Down?

Reply #22 – November 04, 2016, 05:56:14 pm

That solenoid should Pop Off every time your compressor shuts off to Expell moisture from that bowl.

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