aux air compressor for air leveling

[Frank McElroy]

Something doesn't seem right.  I don't think there was ever a dash light for the aux air compressor.  Can you please post a picture?  The stock aux air compressor was powered via a 20 amp circuit breaker located in the front run bay location VCA10.  But, current draw was an issue causing the board to short out or catch fire and a previous owner might have modified the circuit adding a dash light.  OEM Wiring diagrams are in Downloads, Electrical, Wiring Diagrams and look at the 2008-9 dynasty set.

[Tom Whitlow]

Well, we thought this switch controlled the air leveling system aux compressor.   We haven't driven it in more than a year due to my wife's surgery and PT (she had a brain tumor removed).  But, I was moving it to our barn the other day, and when I air leveled, the switch didn't seem to be working,  Previously, we would switch this on and it would have a blue light indicating it was on.  We thought this switch controlled the air leveling compressor.  Perhaps the seller told us this, don't remember now.  We can't find any mention of it in our Operator Manual or any of the accessories documents.   If it doesn't control the air leveling compressor, do you know what it does control?  How should we try to diagnose why it no longer seems to switch on?  Maybe it's just the light that's out?  Air leveling appears to be working normally.

[Frank McElroy]

This sure looks aftermarket to me.  You should have an Aux Air Compressor that would supply air to a small air tank located on the frame rail in the rear by the DS drive axle.  That compressor (mounted on the steer axle H frame) would only be needed when you are parked and in the auto level mode.  While driving it would be turned off.

Likely what happened is that there was an issue with the large printed circuit board in the front run bay (FRB) and the power feed to the compressor was rewired.  Post a few pictures of your FRB and maybe I can spot an extra fuse holder.  Otherwise you will need to follow the wires to that switch to see where it's fused.

[96 EVO]

Owner that made the modification went to the trouble of sourcing an appropriate switch to make it look factory 👍!

[Tom Whitlow]

Here's some photos. 

1.  Wiring coming from back of the switch.
2.  Wiring going into .5" split loom which goes down into FRB.
3.  This is the .5" split loom in the FRB coming from above. Note green, black, and red wires.
4.  I think the red wire goes into a 5A fuse and then to a relay.
5.  From the relay wiring goes into some type15A breaker.  The red wire coming into the breaker comes from the large in bound house battery cable terminal on the FRB left wall.
6.  From the breaker wiring goes back to a small bundle meeting the wiring coming down in the .5" split loom.  Some of the wiring then goes into a .375" split loom and goes back up  I assume this goes to the valid system, but don't know for sure.

I would like to test the switch somehow to determine if the light still works.  And, I would like to test whatever wiring goes to the air leveling compressor to see if it still works.  Anything else I could/should test?  If I determine it's not working, maybe I need to take the compressor out and see if it can be repaired?  Since the air leveling is working fine, is it even worth doing?

 

[Tom Cherry]

1 hour ago, Tom Whitlow said:

Here's some photos. 

1.  Wiring coming from back of the switch.
2.  Wiring going into .5" split loom which goes down into FRB.
3.  This is the .5" split loom in the FRB coming from above. Note green, black, and red wires.
4.  I think the red wire goes into a 5A fuse and then to a relay.
5.  From the relay wiring goes into some type15A breaker.  The red wire coming into the breaker comes from the large in bound house battery cable terminal on the FRB left wall.
6.  From the breaker wiring goes back to a small bundle meeting the wiring coming down in the .5" split loom.  Some of the wiring then goes into a .375" split loom and goes back up  I assume this goes to the valid system, but don't know for sure.

I would like to test the switch somehow to determine if the light still works.  And, I would like to test whatever wiring goes to the air leveling compressor to see if it still works.  Anything else I could/should test?  If I determine it's not working, maybe I need to take the compressor out and see if it can be repaired?  Since the air leveling is working fine, is it even worth doing?

 

OK….lots of experts….and what we, or at least me, need is a rough drawn wiring schematic.  If you pulled out the relay and shot a picture of the bottom or the back, that would help.  I’m assumng the Portugal relay and the resettable circuit (15 A) above it are added….as it don’t look like nothing that Monaco ever installed.  A 75A relay will power my entire front slide’s hydraulic….  So, using one and then protecting at 15A is a bit of overkill….even for me.  MOST folks would have used a 20 or 30 A “Bosch” relay and socket….so, if you ever needed to pull and replace a faulty relay….easy to do.  Just REMEMBER that.

NOW…poor man’s or “fools will guess” things.

There is, I believe, a pressure switch for the AUX compressor.  It is a ON at 90 PSI and OFF at 120 PSI.  When you level amd leave the system in AUTO, it comes on….and then, when someone walks or the system has a wee tiny leak or you have a “Bounce House” event in the MH, AND the pressure drops, the AUX comes on.  BUT….some of us don’t like to hear that rascal cycle on at 3:00 AM.  We leave the system OFF. We never have a corner “droop”.  And we don’t get awakened by our DW saying….”What’s that Noise?”  Yours is, I THINK, in the rear between the drive and tag axles on the ROAD side….a bit of a difficult place, I am told, to werive or sork on.  BUT….right where you sleep.  Mine is next to the Genny and it does make a FUSS.

The switches that control the ON at 90 and OFF at 120 will get moisture in them.  Easy to install….if you don’t have to have arms like Houdini.

SO…..try this….

We DO NOT know if the Aux Compressor still has the auto ON/OFF switch.  It is needed when the pressure to maintain or assist leveling on the house air system is below 90.  Many of us, will start the engine and let it “pop off” and lwvel.  Others let the Aux Compressor come on….

ODDS ARE…..the light is OUT.  But wiyout a circuit?  IF, when you level, you had to turn it ON and the “light” came on….then that will be easy to test.  You NEED to drain the AIR every year…..your manual has specific instructions.  So  do that.  Do NOT restart the engine.  Put the control in to AUTO….and there will be NO pressure and it might have a hissy fit….but will try.  Then go back to the Road Side and listen as you stand at the rear axles.  Then….go back up front.  Turn ON the switch.   Go back or have someone back there.  They could be back there when you try to leve….and with the switch OFF, NOT HEAR the Aux Compressor….communicate through the side window.  
 

THEN, turn ON the switch.  If they yell….ITS RUNNING….  Bingo….the circuit works.  Light is bad.

IF SO….you need a bulb.  BUT HERE are the options.  Use GOOGLE   IRV2 has a thread on how to replace an incandescent bulb with an LED.   Google “Carling Contura Indicator Bulb Replacement”.

https://www.irv2.com/forums/f115/carling-rocker-switch-led-replacement-308066.html

There is a link to a “boater” sight.

There is a special “Carling Actuator Removal Tool” on Amazon.  The REAL one or a knock off.  Both have worked.  You MUST carefully, with the tool, lift and remove the actualor or the “black top”.  Then replace the bulb. I WOULD NOT USE A SCREWDRIVER….buy the tool.

NOW….if you don’t want to take the switch apart…you can buy a new “switch” from Carling.   Call tech support.  That switch will come with a plain Jane operator.  You can remove it.   Put on your jazzy custom one….

there are a LOT of YouTube videos….so go there and use “carling contura switch indicator light” and watch at 10 or so.

[Frank McElroy]

1 hour ago, Tom Whitlow said:

Here's some photos. 

1.  Wiring coming from back of the switch.
2.  Wiring going into .5" split loom which goes down into FRB.
3.  This is the .5" split loom in the FRB coming from above. Note green, black, and red wires.
4.  I think the red wire goes into a 5A fuse and then to a relay.
5.  From the relay wiring goes into some type15A breaker.  The red wire coming into the breaker comes from the large in bound house battery cable terminal on the FRB left wall.
6.  From the breaker wiring goes back to a small bundle meeting the wiring coming down in the .5" split loom.  Some of the wiring then goes into a .375" split loom and goes back up  I assume this goes to the valid system, but don't know for sure.

I would like to test the switch somehow to determine if the light still works.  And, I would like to test whatever wiring goes to the air leveling compressor to see if it still works.  Anything else I could/should test?  If I determine it's not working, maybe I need to take the compressor out and see if it can be repaired?  Since the air leveling is working fine, is it even worth doing?

 

Definitely something added by a previous owner to control operation of the aux compressor likely for the reason I previously stated.

Aside from drawing up a wiring schematic, a voltmeter will quickly tell you if the switch is energizing the relay.  From there you can verify that power is flowing through the fuses.

I'm guessing but likely the switch is energizing the relay to provide power to the aux pump motor.  On the pump will be a pressure switch that turns the pump on/off depending on aux air tank pressure.  The light on the switch could be wired to always come on when the switch is turned on or it could only light when the pump is actually running.  You won't know until you sketch up a wiring diagram.  Keep in mind that the switch might be connecting ground to the relay coil vs providing +12 VDC.

[Tom Whitlow]

I haven’t given up.  I’ve been working on this little nightmare aux compressor since my last post.  Actually, I prepared a previous progress report but the system lost it before I posted it.  This problem began when we noticed that the aux compressor switch on the dash (aftermarket addition by the previous owner?) no longer had the blue lights.  The air leveling system seemed to be working fine even without the switch on.  But, then my wife said, “I don’t ever hear that aux pump up front come on anymore.”  So, I followed some of the wires from the switch down to a relay in the FRB.  I took the relay out and bench-tested it.  It’s good – no problem there.  I checked the breaker and the fuse – all good.  I then took the dash switch out and bench-tested it.  Both LEDs light up.  It’s a five-tab rocker switch and it seems to be in working order.  I supported the frame with 4X4s and crawled under.  I located the aux compressor attached to the DS steer axle.  See photo 150.  I then located the aux compressor tank above the DS drive axle.  See photo 211.  (Thanks to Frank for telling me where to look)  I tried to draw a sketch of what I think the wiring and plumbing are as far as I could see.  Sorry for the quality, there’s just too much and I’m not good at that.  See attachment.  Battery cables, a breaker, a fuse, a relay, a 5-tab switch, a Valid Power Gear control panel, an aux tank, an air filter line, an air line going to the leveling system, check valves, Ts, a pressure switch, and an aux compressor.  What a mess.  Some wires go into split looms and disappear into the top of the FRB.  Some can’t be easily traced.  So, I attached jumper wires to the black and red wires going into the aux compressor.  When I touched them to the pos and neg connections in the FRB, I hear one quick buzz and click from the aux compressor.  Hmm.  So, I put a jumper across the green and black wires going to the pressure switch hoping to eliminate it from the fray.  Back to the batt pos & neg.  Nada, nothing.  So, it's not the pressure switch, relay, dash switch, etc?  Ok, I pulled the aux compressor air lines and cut the wires.  There were a few drops of water in the outbound air line.  I’ve never seen any water when opening the rear or front drain lines.  BTW, kinda interesting that the input air line goes to a round disk-like filter in the FRB right beside where the batt terminals connect to the big PCB.  Perhaps to keep it clean while also creating some air flow very near the PCB batt terminals?  But, that’s also a long way to be sucking the needed air?  So, I pulled the aux compressor out and bench-tested it.  See photo 225.  Dead as a door nail!  The motor is gone.  My wife thinks that the pressure switch went bad and run it to death.  We did have a problem with it running longer times – back when it was working.  I did take the head off just to see how dirty it was and since there’s rust in there, I suspect there must’ve been some water sometime.  See photo 226  No reed switch unless it could be inside the output air nozzle/handle.  I ordered a new pump from eBay - $277, and a new pressure switch from Amazon.  Coulda been worse.  Concept is simple, implementation not so much.  I’m sticking with the original components to keep it simple and not mess with amps and/or wire sizes.  Hopefully, I can close this out in a few days - if my dash switch starts lighting up blue again.

Hand Drawn Wiring & Plumbing Sketch.pdf

The jpg lost the resolution when converted from pdf.  Here's the pdf version.  I hope it's a little clearer.

Hand Drawn Wiring & Plumbing Sketch 2.pdf

[96 EVO]

Posted earlier in this thread, there is another reason it may have run itself to death!

Frank pulled the head off of his, and found a bit of debris, and corrosion on the reed valve, and 'O' ring it seals, that prevents air from the small reservoir tank, bleeding back thru the compressor, causing the compressor to run more than it should be!

I followed his advice, cleaned mine up, and very rarely do I hear my compressor run now!

BTW.... The levelling system can make several small adjustments without the aux compressor needing to 'top up' the levelling tank!

Some of these adjustments will be letting air out of air bags, rather than adding, so those adjustments use no tank air!

Also, that little tank get's fed air from your chassis secondary air tank, so, until that tank drops below 90psi, it will also be used for leveling even with the engine off!

Edited November 13, 2023 by 96 EVO

[Tom Whitlow]

Is there anything I also should check or just replace back on the aux tank that's over the drive axle?  

[96 EVO]

Hey, if the compressor won't run with 12V applied directly too it, it's probably toast! 

[amphi_sc]

BTW, it looks to me like the pressure switch is too low in the air line and could collect moisture.  I think I would raise it above the pump outlet and position it so water could not settle into it.  i.e. let gravity drain any condensed vapor away from the pressure switch.  While you are replacing stuff I'd probably replace that pressure switch while you're redoing the plumbing....could just run a short airline up from the T and zip tie the pressure switch in a higher location. 

I also can't tell if you have a check valve in the airline.  You don't want any between the small air tank and the pressure switch as any leak in the line/fittings would cause that line to drop and short cycle the pump while the tank could very likely have air.  You would want the check valve between the pressure switch and the pump.  (Somehow my coach had it in the wrong location and when a T developed a slight bubble leak the pump would cycle on for 2 or 3 revolutions every 5 minutes as it quickly rebuilt air pressure in the short air line.)

FWIW, JMHO

Edited November 13, 2023 by amphi_sc
Added another thought

[Tom Whitlow]

Yeah, good suggestion on raising the pressure switch as that line is also the drain line.  I already received the new pressure switch via Amazon.  The new Aux compressor is due in tomorrow.  It comes with new fittings and a new check valve.

[Tom Whitlow]

Sorry I haven’t finished this story.  My coach has been in the shop getting new airbags and I couldn’t take photos.  I did install the new aux compressor, and like magic, everything now works properly – I think.  At least the Compressor switch on the IP now works again. See photo attached.  And, of course, the noisy little aux compressor now works again.  I also replaced the inlet air filter in the FRB since a new one came with the aux compressor kit.  See attached photo.  However, I do have one concern.  When the main air tanks are very low, the new aux compressor seems to run endlessly, or at least, for a longer time than I was willing to wait.  I wonder if this indicates that the little check valve that prevents the aux air tank (back over the DS drive axle) from trying to fill the main tanks when they drop below 65 psi?  See attached photo.  I asked my shop to get me a new check valve.  They said they couldn’t find a replacement.  I wonder if Frank might have a part number/source?  As I said before, this system is a simple concept, but the implementation is somewhat convoluted/complicated.  End of story, I hope.

[Frank McElroy]

1 hour ago, Tom Whitlow said:

Sorry I haven’t finished this story.  My coach has been in the shop getting new airbags and I couldn’t take photos.  I did install the new aux compressor, and like magic, everything now works properly – I think.  At least the Compressor switch on the IP now works again. See photo attached.  And, of course, the noisy little aux compressor now works again.  I also replaced the inlet air filter in the FRB since a new one came with the aux compressor kit.  See attached photo.  However, I do have one concern.  When the main air tanks are very low, the new aux compressor seems to run endlessly, or at least, for a longer time than I was willing to wait.  I wonder if this indicates that the little check valve that prevents the aux air tank (back over the DS drive axle) from trying to fill the main tanks when they drop below 65 psi?  See attached photo.  I asked my shop to get me a new check valve.  They said they couldn’t find a replacement.  I wonder if Frank might have a part number/source?  As I said before, this system is a simple concept, but the implementation is somewhat convoluted/complicated.  End of story, I hope.

I don't think your air drawing is accurate.  There should not be a check valve between the pressure switch and the air line going to the small air tank.  There will be an internal check valve inside the compressor head and on mine there is also a check valve at the small air tank.

There should also be another check valve on the airline between the small air tank and the main air tank. If pressure in the main air tank is increasing from the aux compressor air, it's that check valve that's bad and needs to be replaced.  Your aux air compressor doesn't have an air dryer on it and you would be pumping wet air into your dry main air tank.

[96 EVO]

This look like your check valve?

 

[Tom Whitlow]

Frank:

You're correct on the check valve on the airline coming from the aux compressor.  I reviewed my photos and my drawing.  See the attached photo.  I made a mistake on my drawing.   I drew the check valve on the wrong side of the T.  It should've been drawn on the side coming FROM the aux compressor rather than on the side going to the pressure switch.  My aux compressor doesn't have internal check valving.  There's only that check valve in the attached photo coming from the T (outlet from compressor to the small air tank) that also has the pressure switch attached.  I verified the new one was working before I installed it.  I thought the check valve on the small air tank that I circled in one of the photos sent earlier was on the line going TO the main tank.  It has a small red ring on the coupler.  I have no idea where there would be another check valve between the small air tank and the main tank.  I'll need to get under there again and try to follow the air lines - nearly impossible.  Since it may only be a problem when the main tanks drop below 65 psi, I may just give up and let it be.  Worst case is it could cause the aux compressor to run itself to death again.  

I can't identify the check valve with the red ring that's attached to the small tank.  It's completely painted black. 

And, if the aux compressor starts running continuously, I always have the switch on the IP to shut it off.  Maybe that's why it's there?

[96 EVO]

21 hours ago, Tom Whitlow said:

  I have no idea where there would be another check valve between the small air tank and the main tank.   

 

The air line leaving your chassis dry tank going to your leveling tank, will have a pressure protection valve (PPV), screwed into the dry tank. It will allow air to flow one direction, from the chassis tank to the leveling tank. 

Once the pressure in the chassis tank drops to the PPV's shut off point, air doesn't move either direction!

Sounds like Frank's Dynasty get's air from the primary tank. Pretty sure my Scepter uses the secondary tank.

Edited December 24, 2023 by 96 EVO

[amphi_sc]

Just food for thought.  When I worked on my system I also changed the compressor power source as coming from the house side tapping in at the rear run box.  The original power source from the front run box thru the pressure switch now just powers a 30a relay.  Previously I'm guessing the pressure switch contacts were trying to carry too much current and caused me problems when I changed to a Viair compressor when my OEM died.  It also allowed me to run a heavier wire for power and side effect of not draining my chassis batteries when my Big Boy needs cleaning. ( That seems to catch me off guard when I get lazy and don't check the voltages on the Big Boy after parking for what will be a few weeks ... Only find out much later the Big Boy is warm but chassis bats are very low and thus time to clean those contacts again.)

BTW, The factory used a push to connect T vs DOT compression fittings to my pressure switch which eventually slightly leaked causing the compressor to run more than needed. Seems like the factory loved push to connect fittings as I've observed when replacing several over the years with compression types.

FWIW

[Frank McElroy]

On 12/23/2023 at 4:15 PM, Tom Whitlow said:

Frank:

My aux compressor doesn't have internal check valving.  There's only that check valve in the attached photo coming from the T (outlet from compressor to the small air tank) that also has the pressure switch attached.  I verified the new one was working before I installed it.  I thought the check valve on the small air tank that I circled in one of the photos sent earlier was on the line going TO the main tank.  It has a small red ring on the coupler. 

In a past picture posted of your compressor head, under the metal reed valve there should be an O-ring.  When the reed valve rests on that O-ring, it acts like an internal check valve meaning that you really don't need an external check valve on the compressor.  Having one is OK but not as good as having a working internal reed check valve.  The nice part about an internal reed check valve in the compressor head is that on the air intake stroke, the volume of air between the internal head reed check valve and the external one won't also count as intake air.  This makes the compressor more efficient.  Often, that internal reef check valve becomes dirty and when that happens the compressor needs to run a lot longer.  I've even seen posts where folks advise to just add an external check valve rather than cleaning the internal reed valve O-ring - in my opinion that's bad advice.

Ben is correct, you have a failed PPV valve on your rear main air tank that feeds the small aux air tank.  Either you should replace that PPV valve or don't run your Aux air compressor.  The reason is that if you use your aux air compressor, it also puts WET air into your main DRY air tank.  Your aux air compressor does not have an air dryer on it.  Putting WET air into a DRY air tank is not good for your air brake system.

[Tom Whitlow]

Frank

So you think that little metal flap on the top of the cylinder is a reed valve?  And, if so, should I remove the current check valve in my system (see the second photo)?  And, do you know where the air lines on the aux tank (back over the DS drive axle) might be going (third photo)?  I thought the line on the right (with the red ring) was the line coming FROM the aux compressor.  And the lines coming from the T on the bottom of the tank were going TO the leveling system and the main tank.  Is it the other way around?  I need to know what line to try to follow to find the PPV so I can replace it.  So, many of the airlines just disappear into bundles of split loom.   Maybe I should just shut off the aux compressor at my dash switch and quit worrying about it?

[Frank McElroy]

1 hour ago, Tom Whitlow said:

Frank

So you think that little metal flap on the top of the cylinder is a reed valve?  And, if so, should I remove the current check valve in my system (see the second photo)?  And, do you know where the air lines on the aux tank (back over the DS drive axle) might be going (third photo)?  I thought the line on the right (with the red ring) was the line coming FROM the aux compressor.  And the lines coming from the T on the bottom of the tank were going TO the leveling system and the main tank.  Is it the other way around?  I need to know what line to try to follow to find the PPV so I can replace it.  So, many of the airlines just disappear into bundles of split loom.   Maybe I should just shut off the aux compressor at my dash switch and quit worrying about it?

Once leveled, my coach stays level for months.  So I don't need to use the aux compressor.  The circuit breaker is removed.

On the attached picture, the black line on top goes to the aux compressor. On the tank tee, the large green line goes to the main rear air tank, the smaller red line goes to the rear bleed valve.  The small black line (hard to see in the picture) just above the pressure relief valve goes to feed the air bag valve control manifolds.

[Newcsn]

On 3/16/2023 at 2:42 PM, Ivylog said:

Decided to remove and inspect my aux compressor from behind the front axle because it took for ever to build pressure and it’s very noisy. All of the inside is black due to poor filtering of the air and the cylinder is scored badly. Honed it and sanded the lip of the piston. Still just as noisy and I’ve already mounted another compressor up front next to the generator. Has to be a better location and it’s a lot quicker than the Power Gear.

MODERATOR NOTE.  The discussion about the NEED for or the CAUSE of a Generator NOT starting properly and putting an up front battery has MORPHED.  All the SUBSEQUENT REPLIES TO THIS TOPIC HAVE BEEN MOVED.... Members requested this housekeeping for information and ability to search and use....

END OF EDIT....

This is the topic where the posts were moved to....NOW COMPLETED....see the link below...

@Ivylog Just ran across your pic of the new compressor/battery mount. What brand of compressor is that? And, do I assume correctly that the battery is to start the genset? If so, I’ve been considering doing the same & would value feed back on wiring & components necessary to put a genset starting battery up front w/ short cable runs. Will the alternator on the genset charge this battery/how do you keep it charged?  Thanks

[Ivylog]

Yes the battery is #4 on the engine side mounted next to the generator. Tied into the engine’s lug on the outside of the FRB so charged by the engine’s alternator. I find mixed results the my 10K has its own alternator… don’t see one on it.

Air compressor is off EBay.

[Monte Roger Fautin]

Greetings,

My compressor for keeping the coach level runs every 15 minutes for 30 seconds. Must be a small air leak, plus the compressor is rather noisy.

Temperature seems to affect frequency too( I am in Vegas, January).

What's the best remedy? HELP