Auxciliary compressor won't run

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Auxciliary compressor won't run

May 24, 2018, 08:54:43 pm

It's a 2001 U320 Thomas model 405ADC38/12F. Not sure when it quit. Put the slide out last week and pulled it back in without noticing anything unusual. Went to put it out an hour later (well after the yellow light came on) and heard the loud noise of the sides of the slide rubbing against the inflated bladder. I let lt deploy, noticed the bladder had not deflated, and retracted it immediately.
Since then I checked and the compressor will not run. I don't have a inline fuse and the circuit breaker (CB) that is 15 amp looks fine. Where do I start to see/check if the compressor is good or done for? Or is there something else I should check?

Re: Auxciliary compressor won't run

Reply #1 – May 24, 2018, 09:54:34 pm

Check the pressure control switch. Mine was sticking and it would not come on. Take the cover off the awitch and you can see the contactor bar. Use a screw driver or something insulated and push it open. Mine goes out towards the outside of the coach. If the compressor has power it should start.

On the 2001 (likely the 99s and 00s) the bladder manifold uses compressed air to create a vacuum to deflate the bladder. When you turn on the key you should hear the air flowing through the manifold. The yellow light comes on after about 40 seconds. There is no vacuum measurement. That came after 2001.

With the slide in it is very easy to see the bladder at the front and rear and along the top. Look, make sure the bladder is deflated, there should be 1/4" or more clearance. With the slide out you will still be able to see the bladder at the front and rear, look for the bladder to be open. Look for daylight.

You should never hear the slide squealing when the slide moves in or out. That is a sure way to damage the bladder. If it is squealing then stop, turn the key off, wait for a minute and turn it back on. You should hear the compressor running and an air rushing sound. Wait until you see daylight. Then move in or out. Worst case if it is squealing and you can't do anything about it use a spray bottle with soapy water as a lubricant.

Re: Auxciliary compressor won't run

Reply #2 – May 24, 2018, 10:41:07 pm

Jon, I am not sure if your situation is an emergency? You stuck somewhere and need to leave and the aux will not run?

IF that is the case and the fix Roger suggested does not activate the aux, as a get you by action, I believe that you can add air to the third front air tank that supplies air to the deflate mechanism. (I am assuming you have no air in the tank in order to deflate, that being because the aux did/does not pressurize the third tank) There is a way to splice into the air line to the third tank and use an portable compressor to fill the third tank and with it full I think you could deflate the bladder......anyone disagree? I feel pretty good you do not have to have the aux running if you have pressure in the third tank. (Love the air pressure gauge I have on that third tank, placed right at the aux compressor so I know what is going on.)

That all said, you must be very careful messing around with air lines and pressures. If you were to splice in, you must not disrupt the brake mechanism, for example, and I think you would need pro help doing this though I know it can be done.

You could add air to the third tank.....just my opinion....by using the air tank bleed valve on the bottom of the tank to introduce the air. The trick I think would be to get a way to fit the portable compressor into it, I have for example and air gun with a rubber tip nozzle that I have assumed would work.

I hope others join into this possibility, I do not want you getting hurt but it is a means I and a tech devised when it seemed I lost the aux compressor on a trip.

Hopefully Roger has gotten you there. By the way, the small blade fuse on the compressor takes careful inspection to determine if it has blown....maybe just try another one?

Re: Auxciliary compressor won't run

Reply #3 – May 25, 2018, 08:56:06 am

Unfortunately I am in the same situation with the 12v compressor not running and its interesting and a learning process why. While I wish it was a easier way to diagnose it, truth is I haven't pulled out the voltmeter yet, jacked my back up and lying down in the bay has been trying.... Really need this compressor running as it's a sad look to have such a magnificent beast leaning to it side like a sad sack.

Re: Auxciliary compressor won't run

Reply #4 – May 25, 2018, 09:04:29 am

Quote from: bobfnbw – May 25, 2018, 08:56:06 am

Unfortunately I am in the same situation with the 12v compressor not running and its interesting and a learning process why. While I wish it was a easier way to diagnose it, truth is I haven't pulled out the voltmeter yet, jacked my back up and lying down in the bay has been trying.... Really need this compressor running as it's a sad look to have such a magnificent beast leaning to it side like a sad sack.

If the coach drops the pressure in the air bags quickly the small 12 volt air compressor that came in our '99s will wear out fast. They were meant to keep up with very small leaks in the leveling system. Mine never came on so I had to manually get the coach out of level with low tank pressure to find out that it works.

Re: Auxciliary compressor won't run

Reply #5 – May 25, 2018, 09:51:35 am

When you get somewhere, and are ready to level leave the engine running and press the air button twice. The coach should level itself. Press the off button and then quickly press the air button once. That puts it in manual mode. Shut the engine off.

If the coach leans to one side after a day or so, let some air out of the opposite side. Front to rear is the same but harder to make as much change just letting some air out. If your compressor is working and you call for air to raise one side or the other the compressor will come on.

In automatic it will do this by itself every 30 minutes or so. The compressor may or may not come on depending on whether you need air. Ours stays pretty close so only one or two small tweaks a week is good enough for us. Saves wear and tear on the compressor.

If you are level and then lean quickly to one side then you have a pretty big air leak, air bag, leveling manifold, service air tank, ride height valve, check valves and every fitting along the way. I would chase down a big leak. Small slow leaks are a minor issue that need not be fixed right now (at least not for me)

Re: Auxciliary compressor won't run

Reply #6 – May 25, 2018, 12:38:27 pm

Roger, thanks for the reply I'm on my way to storage to do the things you have suggested.
Mike, not stuck anywhere. We just didn't use slide out on this trip.
I'm hoping to find my answer today. If not I'll just keep trying.

Re: Auxciliary compressor won't run

Reply #7 – May 25, 2018, 01:05:05 pm

Quote from: Roger & Susan in Home2 – May 25, 2018, 09:51:35 am

If you are level and then lean quickly to one side then you have a pretty big air leak, air bag, leveling manifold, service air tank, ride height valve, check valves and every fitting along the way. I would chase down a big leak. Small slow leaks are a minor issue that need not be fixed right now (at least not for me)

Yes, I have a big leak and will have to fix it. Sure want to know why the 12v compressor isn't coming on though.

Re: Auxciliary compressor won't run

Reply #8 – May 25, 2018, 03:52:48 pm

You can pressurize the tank by connecting a compressor to the tire inflation outlet. This way you will "back fill" the tank. Be aware that you will be bypassing the air dryer so unless there is a moisture trap and a desiccant cartridge in the line you will introduce some moisture in the system. The leveling system will then work. As I don't have slides I cannot comment on it working for them but I believe they use the same tank. Don't fill above 120psi.

Keith

Re: Auxciliary compressor won't run

Reply #9 – May 25, 2018, 04:30:11 pm

Checked the pressure control switch, nothing. Check everything else I'm capable of, still won't run, and then decided to just remove the compressor and order a new one. It will either fix my problem, or I will have a nice spare. Wish me luck.
Life is just to short to keep working in that cramped space at my age.

Re: Auxciliary compressor won't run

Reply #10 – May 25, 2018, 06:13:08 pm

Don't buy a new compressor (about $750) until you determine that 12v is available at the compressor and it still won't run. If you are going to get one I have a rebuilt compressor like the one you have or buy the bigger one used on the 2002 and later coaches.

Not sure what build number you have but on my 2001 U320 (#5879) connecting a compressor to the aux air outlet will not put air into the HWH bladder tank. It will supply air to the leveling manifolds and allow you to level the coach or raise it. If your rear brake service tank pressure is below the pressure protection valve low set point then it will prevent air from going into that tank. The aux air outlet cannot add air to the front brake service tank.

Re: Auxciliary compressor won't run

Reply #11 – May 25, 2018, 06:19:48 pm

Jon, I have inline fuse plus CB. The inline fuse may not have been standard, I do not know but from Tech talk one time I believe it is standard. And some people accidentally got 5 am fuses that in time blow. I think it shows in the manual with the coach that it to be higher than 5 amp.

Keith, I am not sure the third tank used by the 01 for level maintenance (after the main tanks are depleted below about 70) can be backfilled via the air outlet but if you get the main tanks filled, it will level as long as they are above about 70 psi after which case the aux third tank gets used. As far as I know the slide bladder depends on the third tank, not the main tanks ?

Re: Auxciliary compressor won't run

Reply #12 – May 25, 2018, 09:22:41 pm

Look at the air system drawing in reply #10 for U320's, build numbers from 5871 to 5919. Your plumbing may have been altered. Your coach may well have a different drawing depending on your build number and coach model.

As built for this range of build numbers (starting at #5871) in the U320 models, the HWH tank can only be filled by the HWH compressor. Check valves prevent airflow against the arrow direction.

The HWH compressor and the front (left) and rear (right) service tanks feed the leveling manifolds. Adding air into the aux air connection also feeds both of the leveling manifolds.

The right tank pressure protection valve (if this behaves as a standard pressure protection valve does) prevents air flow in both directions if the air pressure in the right tank falls below about 70 psi which means air from the aux air connection will not go into the rear (right) tank when its pressure is low. Based on the air plumbing drawing no matter what is going on in the front (left) tank no air from the aux air connection will ever get into that tank.

The pressure protection valve closes when the pressure in the tank falls below about 70 psi. When this occurs air from this tank cannot be used for leveling or aux air. It does not prevent the air pressur in the tank to to continue to leak down from any other of the many connections.

This corresponds to my experience adding air through the aux air connection.

Re: Auxciliary compressor won't run

Reply #13 – May 26, 2018, 12:16:17 am

Roger, just FYI to you probably only.....I had check valve failure and the aux pressurized all three tanks at same time. So the left can get air. Went from 60 to 70 psi in all three and I shut it down to prevent damage. By the way, my aux is now turned up to 100 psi.

Re: Auxciliary compressor won't run

Reply #14 – May 26, 2018, 10:35:53 am

Quote from: Michael & Jackie – May 26, 2018, 12:16:17 am

Roger, just FYI to you probably only.....I had check valve failure and the aux pressurized all three tanks at same time. So the left can get air. Went from 60 to 70 psi in all three and I shut it down to prevent damage. By the way, my aux is now turned up to 100 psi.

I had same problem Mike, twice! one on one tank, then on the other. Ended up putting a switch [like many others have] on the compressor before I got replacement check valves.

Re: Auxciliary compressor won't run

Reply #15 – May 26, 2018, 12:31:44 pm

Switch and gauge one of better and least expensive things have done

Re: Auxciliary compressor won't run

Reply #16 – May 26, 2018, 11:12:53 pm

Quote from: Roger & Susan in Home2 – May 25, 2018, 06:13:08 pm

Don't buy a new compressor (about $750) until you determine that 12v is available at the compressor and it still won't run. If you are going to get one I have a rebuilt compressor like the one you have or buy the bigger one used on the 2002 and later coaches.

Roger, For my information... do you have a part number for that compressor for the 202 coaches? Also what about rebuilding them?
Bob

Re: Auxciliary compressor won't run

Reply #17 – May 27, 2018, 12:41:18 am

Bob, this is the rebuild kit for the 2001 compressor.
Thomas Service kit, For 5Z349 SK405DCMAJ | Zoro.com

I am not sure of the PN for the bigger compressor, I will keep looking

Re: Auxciliary compressor won't run

Reply #18 – May 27, 2018, 12:57:57 am

cannot remember why.....cost maybe....that I was discouraged by MOT from converting to the larger compressor that for the 2002 was designed size to operate the awning too. Believe Aubrey told me that.

Anyway....the aux compressor lets moisture into our systems. Can cause problems if dust present. I asked Aubrey and couple of others and they discouraged adding on or converting to the dri-rite desiccant system, best to stay with the condenser/exhaust on the OEM. Strong feelings about that. Just FYI

Re: Auxciliary compressor won't run

Reply #19 – May 27, 2018, 05:06:08 am

Quote from: Roger & Susan in Home2 – May 27, 2018, 12:41:18 am

Bob, this is the rebuild kit for the 2001 compressor.
Thomas Service kit, For 5Z349 SK405DCMAJ | Zoro.com

I am not sure of the PN for the bigger compressor, I will keep looking

Thank you sir! What about the electrical parts?

Re: Auxciliary compressor won't run

Reply #20 – May 27, 2018, 08:50:55 am

FT went to the bigger compressor to actuate the big awning (many ended up adding a small 120v compressor just for the awning) and for the VacuFlush (turbo turd 3000) toilet. Both of these have been problem areas for many. They either work well or are constant headaches.

The bigger compressor is $300 - $400 more depending on the source. Fitting it in where the 2001 compressor goes might be an issue. Everything else should be compatible. In 2002 the air diagrams shows the bigger compressor feeding the "wet" tank (which feeds the front and rear service tanks). A lot more air to compress.

And dry moisture free air is required. The 2002 and beyond (some 2001s too) have a dryer and descicant bowl which requires maintenance.

Re: Auxciliary compressor won't run

Reply #21 – May 27, 2018, 09:04:49 am

You know why it is called the wet tank?

(More info from Aubrey when he told me not to convert to drier or larger compressor)

I wrote that the aux can introduce moisture to various tanks and which tanks get it depend on the check valves operating properly. The moisture can damage the check valves related to slide and level parked and accentuate problems

But in early days the issue was much different. The wet tank was literally the means by which moisture was removrd, drained, from the system. Imagine the volume of air, and moisture sans a drier, going thru the system. So it generally condensed in that tank and every trip you drained.

Well, that is what I heard. Am intersted if anyone knows that not correct, that has always had an engine cimpressor drier?

Re: Auxciliary compressor won't run

Reply #22 – May 27, 2018, 09:37:25 am

Quote from: Michael & Jackie – May 27, 2018, 09:04:49 am

You know why it is called the wet tank?

(More info from Aubrey when he told me not to convert to drier or larger compressor)

I wrote that the aux can introduce moisture to various tanks and which tanks get it depend on the check valves operating properly. The moisture can damage the valves and accentuate problems

But in early days the issue was much different. The wet tank was literally the means by which moisture was removrd, drained, from the system. Imagine the volume of air, and moisture sans a drier, going thru the system. So it generally condensed in that tank and every trip you drained.

Well, that is what I heard. Am intersted if anyone knows that not correct, that has always had an engine cimpressor drier?

Had a 4106 that had no air dryer. Used to drain wet tank [and dry tanks] daily. Not much out of dry tanks but sometimes a cup or 2 out of the wet tank.

Re: Auxciliary compressor won't run

Reply #23 – May 27, 2018, 09:40:46 am

Quote from: Michael & Jackie – May 27, 2018, 09:04:49 am

You know why it is called the wet tank?

(More info from Aubrey when he told me not to convert to drier or larger compressor)

I wrote that the aux can introduce moisture to various tanks and which tanks get it depend on the check valves operating properly. The moisture can damage the valves and accentuate problems

But in early days the issue was much different. The wet tank was literally the means by which moisture was removrd, drained, from the system. Imagine the volume of air, and moisture sans a drier, going thru the system. So it generally condensed in that tank and every trip you drained.

Well, that is what I heard. Am intersted if anyone knows that not correct, that has always had an engine cimpressor drier?

My crane has no drier and it needs to be drained after each days use. It collects a lot of moisture, but no air valves except for the brakes. It is a 1981 International and the moisture hasn't killed it yet.

Re: Auxciliary compressor won't run

Reply #24 – May 27, 2018, 10:05:21 am

A friend of mine is a diesel mechanic for one of the large food service distributors in Knoxville, TN.

He told me that most of the drivers never bleed their tanks, so when the rigs come in for service he sometimes finds as much as
1/2 tank of water.

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