Air Tank Switch

Topic: Air Tank Switch (Read 1732 times) previous topic - next topic

Air Tank Switch

September 06, 2017, 06:58:47 pm

For those of you that have a air tank switch on the side consul, what exactly does it do? I see it operates a solenoid valve on the discharge of the 12 volt compressor, and I thought it would allow the little compressor fill all the tanks. It turns out, 12 volt compressor fills all tanks anyway. My air schematic does not even show this solenoid valve, but I am sure it is there for a reason.
Installed new solenoid valve and got same results.

Re: Air Tank Switch

Reply #1 – September 06, 2017, 07:09:54 pm

Yup, Some years had that switch..for a manual override. to maintain air pressure in all tanks... slow but it works, deleted in newer coaches tho.

Re: Air Tank Switch

Reply #2 – September 06, 2017, 07:17:20 pm

Quote from: saddlesore – September 06, 2017, 07:09:54 pm

Yup, Some years had that switch..for a manual override. to maintain air pressure in all tanks... slow but it works, deleted in newer coaches tho.

Mine fills all the tanks even when switch off and valve closed.

Re: Air Tank Switch

Reply #3 – September 06, 2017, 07:20:36 pm

Mine has the switch but never hear anything when I switch it to on or off.. if I turned it to the on position , what is supposed to happen?

Re: Air Tank Switch

Reply #4 – September 06, 2017, 07:27:18 pm

Quote from: DavidS – September 06, 2017, 07:20:36 pm

Mine has the switch but never hear anything when I switch it to on or off.. if I turned it to the on position , what is supposed to happen?

If you look at the discharge of the 12 volt compressor, you will see one line that goes to the small slide seal tank and 6 packs and another through a solenoid valve. That valve is operated by the switch and I assumed it would fill the main tanks when operated, but mine fills the main tanks even when not operated. Thinking Foretravel put it there so you could fill all tanks at campground without starting engine.
But mine fills tanks whether on or off.

Re: Air Tank Switch

Reply #5 – September 06, 2017, 07:52:54 pm

At least in a 2003, the "Air Tank" switch opens a solenoid to allow the aux compressor to air up the main tanks without the main coach engine running. As some have suggested, this is to allow "polite" preparation to depart.

If your aux compressor airs up your main tanks without this switch "on" (you can see this on your Driver Info Center - the A and B tanks rise in pressure when the aux compressor is running even with the switch off), your solenoid is leaking through.

This is NOT GOOD! The desiccant charge on the aux compressor is insufficient to provide adequate dry air to those tanks for consistent use. You should service that solenoid valve. It's a a typical normally-closed HWH solenoid valve.

Re: Air Tank Switch

Reply #6 – September 06, 2017, 07:59:36 pm

Quote from: Michelle – September 06, 2017, 07:52:54 pm

At least in a 2003, the "Air Tank" switch opens a solenoid to allow the aux compressor to air up the main tanks without the main coach engine running. As some have suggested, this is to allow "polite" preparation to depart.

If your aux compressor airs up your main tanks without this switch "on" (you can see this on your Driver Info Center - the A and B tanks rise in pressure when the aux compressor is running even with the switch off), your solenoid is leaking through.

This is NOT GOOD! The desiccant charge on the aux compressor is insufficient to provide adequate dry air to those tanks for consistent use. You should service that solenoid valve. It's a a typical normally-closed HWH solenoid valve.

I agree completely, but with valve closed [even bought a new one] the a&b tanks fill as the 12 volt compressor runs. My air drawings dated 02 do not even show this valve.

Re: Air Tank Switch

Reply #7 – September 06, 2017, 08:32:07 pm

Quote from: jcus – September 06, 2017, 07:59:36 pm

I agree completely, but with valve closed [even bought a new one] the a&b tanks fill as the 12 volt compressor runs. My air drawings dated 02 do not even show this valve.

for a 2003 with tag, in the Media -> Foretravel Library -> Schematics look at

http://www.foreforums.com/index.php?action=media;sa=item;in=3301#viewitem

http://www.foreforums.com/index.php?action=media;sa=item;in=3302#viewitem

Re: Air Tank Switch

Reply #8 – September 06, 2017, 09:16:19 pm

Quote from: Michelle – September 06, 2017, 08:32:07 pm

for a 2003 with tag, in the Media -> Foretravel Library -> Schematics look at

http://www.foreforums.com/index.php?action=media;sa=item;in=3301#viewitem

http://www.foreforums.com/index.php?action=media;sa=item;in=3302#viewitem

Thanks for the help Michelle, one schematic shows with solenoid, and one without. Think its time block up coach [wooden] and get my creeper out and trace some lines.

Re: Air Tank Switch

Reply #9 – September 06, 2017, 09:46:24 pm

Quote from: jcus – September 06, 2017, 09:16:19 pm

Thanks for the help Michelle, one schematic shows with solenoid, and one without. Think its time block up coach [wooden] and get my creeper out and trace some lines.

Solenoid (IIRC) and check valve will be in the aux compressor bay

Re: Air Tank Switch

Reply #10 – September 06, 2017, 09:55:18 pm

Quote from: Michelle – September 06, 2017, 09:46:24 pm

Solenoid (IIRC) and check valve will be in the aux compressor bay

Yes, I changed the solenoid valve on line 76 on bottom discharge of "T" of discharge of aux compressor, however do not see a check valve in that line in aux compressor [electronics] bay.

Re: Air Tank Switch

Reply #11 – September 08, 2017, 04:52:51 am

To build on the good advice above, I'd add that in our coach the protection and check valves attached to the front and rear tanks had failed. Please see attached air schematic and the first photo. The check valves and protection valves are arranged a little differently on the front and rear tanks but the photo should aid in identifying the components. When both the check and protection valves fail, air may travel in wrong direction from line #57 and/or line #50 into the effected tank.

There are two styles of check valves in the utility bay. The first is shown in photo 2 and is the same style as the ones on the air tanks. It is in air line #57.

The other check valves are shown in photo 3 and are small in-line parts that look like a brass NPT pipe nipple. IIRC there are two of them.

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Re: Air Tank Switch

Reply #12 – September 08, 2017, 09:54:58 am

Good info Mark. My check and protection valves appear to be doing there job. I notice your schematic does not show the solenoid valve in line 76. In pic 4, I can see a ball valve where my solenoid valve is, below the "t". Strange, the unattached wire laying there is the one that powers the solenoid on my coach. Maybe po removed it, or factory changed mid year. I do know my coach has 2 separate 110 bolt Aqua-hot heating elements, something I had not heard of.
Mark is that the same coach in all the pics? Maybe my eyes are going, but it appears you have a solenoid in pic and a valve in pic 4?

Re: Air Tank Switch

Reply #13 – September 08, 2017, 10:27:55 am

Quote from: jcus – September 08, 2017, 09:54:58 am

Good info Mark. My check and protection valves appear to be doing there job. I notice your schematic does not show the solenoid valve in line 76. In pic 4, I can see a ball valve where my solenoid valve is, below the "t". Strange, the unattached wire laying there is the one that powers the solenoid on my coach. Maybe po removed it, or factory changed mid year. I do know my coach has 2 separate 110 bolt Aqua-hot heating elements, something I had not heard of.
Mark is that the same coach in all the pics? Maybe my eyes are going, but it appears you have a solenoid in pic and a valve in pic 4?

IMHO the schematics are at best only reasonable approximations of what was actually installed. For example, you also won't see the OEM desiccant dryer and filters nor the check valves shown in photo 3. That said they've been invaluable in learning and working on the system.

Your eyes are not failing, they are very sharp! The picture with the solenoid was taken prior to purchasing the coach. After I discovered that the solenoid had failed, I installed a ball valve in its place. The wire you see will be to power the solenoid when it rises to the top of the to do list.

Re: Air Tank Switch

Reply #14 – September 09, 2017, 04:52:23 pm

Thanks to Michelle and especially Mark, who instructed me on how to read an air schematic properly. Appears problem, as he stated, is one or two tank check valves leaking by. The old saying "you are never too old to learn something new" is very true.

Re: Air Tank Switch

Reply #15 – September 09, 2017, 07:43:29 pm

Quote from: jcus – September 06, 2017, 09:16:19 pm

Thanks for the help Michelle, one schematic shows with solenoid, and one without. Think its time block up coach [wooden] and get my creeper out and trace some lines.

Yeah - I "assumed" the air schematic from our 2003 coach was correct

Looks like it was a pre-air tank switch air schematic.

Dan W. can confirm - he has the originals - but I see that the FT one all of us have posted is missing that, and the second one that's more CorelDraw-y has the solenoid.

Re: Air Tank Switch

Reply #16 – September 09, 2017, 07:52:02 pm

Quote from: Michelle – September 09, 2017, 07:43:29 pm

Yeah - I "assumed" the air schematic from our 2003 coach was correct Looks like it was a pre-air tank switch air schematic.

Dan W. can confirm - he has the originals - but I see that the FT one all of us have posted is missing that, and the second one that's more CorelDraw-y has the solenoid.

Yes, whoever did the second one must have seen the "correct schematic" or traced out the lines and drew it himself.

Re: Air Tank Switch

Reply #17 – September 12, 2017, 08:37:03 pm

When i turn our Air Tank Switch on (2003 GV 295) I don't here anything. If i were to leave it on over night does it suppose to maintain the air pressure in the air tanks?

I had never noticed but just on this trip, when i leave the HWH on it maintains the level by slowly letting air out. It never puts air in. So in 3-4 days air is gone and bags are flat. Then i have to run the engine to refill the tanks. Something must not be working right?
Thank you,
AL

Re: Air Tank Switch

Reply #18 – September 12, 2017, 08:43:56 pm

Quote from: propman – September 12, 2017, 08:37:03 pm

When i turn our Air Tank Switch on (2003 GV 295) I don't here anything. If i were to leave it on over night does it suppose to maintain the air pressure in the air tanks?

You can test the Air Tank switch to see if it's working properly by watching the Driver Info Center A and B tanks with the ignition on (at Accessory or something like that - where you can see dash activity but haven't started the coach).

If you flip the switch, the aux compressor should come on and you should see the A and B tanks increase in pressure (up to the limit of the aux compressor.

If the tanks are low and nothing happens when you turn the switch on, it's possible the switch or the solenoid are bad/disabled.

If you see the A and B tanks increase in pressure when the aux compressor is running BUT you don't have the Air Tank switch on, the solenoid is leaking through and should be replaced.

You should NOT leave the Air Tank switch on. It's purpose is solely to allow you to air up the coach most of the way to depart in the morning without running the coach engine until absolutely necessary - basically to be a good neighbor at a campground. The desiccant charge on the aux compressor is MUCH TOO LITTLE to use the Air Tank switch regularly or to leave it on.

Re: Air Tank Switch

Reply #19 – September 12, 2017, 09:06:32 pm

Quote from: propman – September 12, 2017, 08:37:03 pm

When i turn our Air Tank Switch on (2003 GV 295) I don't here anything. If i were to leave it on over night does it suppose to maintain the air pressure in the air tanks?

I had never noticed but just on this trip, when i leave the HWH on it maintains the level by slowly letting air out. It never puts air in. So in 3-4 days air is gone and bags are flat. Then i have to run the engine to refill the tanks. Something must not be working right?
Thank you,
AL

Do you ever hear the hwh compressor running? If not, would start your troubleshooting with it.

Re: Air Tank Switch

Reply #20 – September 13, 2017, 08:13:44 am

Quote from: propman – September 12, 2017, 08:37:03 pm

I had never noticed but just on this trip, when i leave the HWH on it maintains the level by slowly letting air out. It never puts air in. So in 3-4 days air is gone and bags are flat. Then i have to run the engine to refill the tanks. Something must not be working right?

Yes, something is not working right. If your air tanks are empty, and you press one of the manual "RAISE" buttons on the HWH panel, then the "AUX" compressor should run. I think this statement is correct no matter what HWH Series (air) system is fitted to your coach.

Re: Air Tank Switch

Reply #21 – September 13, 2017, 09:13:33 am

The air tank switch in probably not your first problem, with slides the compressor needs to maintain pressure to the seals and to deflate and inflate them after operation. You should hear the comp running sometimes especially after moving a slide, [if main engine compressor has not filled tanks] On mine I have a switch next to compressor and a gauge. .

Re: Air Tank Switch

Reply #22 – September 13, 2017, 10:44:25 pm

Quote from: Michelle – September 12, 2017, 08:43:56 pm

You can test the Air Tank switch to see if it's working properly by watching the Driver Info Center A and B tanks with the ignition on (at Accessory or something like that - where you can see dash activity but haven't started the coach).

If you flip the switch, the aux compressor should come on and you should see the A and B tanks increase in pressure (up to the limit of the aux compressor.

If the tanks are low and nothing happens when you turn the switch on, it's possible the switch or the solenoid are bad/disabled.

If you see the A and B tanks increase in pressure when the aux compressor is running BUT you don't have the Air Tank switch on, the solenoid is leaking through and should be replaced.

You should NOT leave the Air Tank switch on. It's purpose is solely to allow you to air up the coach most of the way to depart in the morning without running the coach engine until absolutely necessary - basically to be a good neighbor at a campground. The desiccant charge on the aux compressor is MUCH TOO LITTLE to use the Air Tank switch regularly or to leave it on.

not to ask a dumb question but where is the air tank switch located??? on a 2000 u320?

Re: Air Tank Switch

Reply #23 – September 14, 2017, 01:31:29 am

I don't have any slides.
Electric "HWH" compressor is working, such as when i "press one of the manual "RAISE" buttons" slow but it does work

When i do this "You can test the Air Tank switch to see if it's working properly by watching the Driver Info Center A and B tanks with the ignition on (at Accessory or something like that - where you can see dash activity but haven't started the coach)." I get nothing. The Air Tank Switch is not activating anything.

Yesterday (Tuesday morning ) after HWH was left in auto mode the bags were empty, I noticed for 3 days or so HWH kept it level by letting air out never adding air in. Tuesday I started the engine and let the engine compressor fill up the bags and the tanks, then i had the HWH do the leveling but this time for over night i did not leave HWH on auto level mode. This morning we were still level and bags were not flat, all with air.

Re: Air Tank Switch

Reply #24 – September 14, 2017, 07:37:32 am

Quote from: propman – September 14, 2017, 01:31:29 am

Yesterday (Tuesday morning ) after HWH was left in auto mode the bags were empty, I noticed for 3 days or so HWH kept it level by letting air out never adding air in. Tuesday I started the engine and let the engine compressor fill up the bags and the tanks, then i had the HWH do the leveling but this time for over night i did not leave HWH on auto level mode. This morning we were still level and bags were not flat, all with air.

Well, you do have a puzzling situation here, because these two "tests" are contradictory. But then, air system problems are never simple.

In the first test, you say the HWH system kept the coach level by releasing air. This is what should happen, but only if one or more of the air bags are leaking down (losing pressure). Every 30 minutes, when the HWH panel wakes up, if the coach is not level, then (initially) air will be released to regain level. This indicates the level sensor is working, and the system is responding correctly (up to the point where the compressor should run).

BUT, in the 2nd test, when you start out level, and leave the HWH auto level turned off, the coach stays level. This would indicate that none of the air bags are leaking down (losing pressure). WT..IGO?

SO, the question is: why do the air bags leak down in the first test, but not in the 2nd test? At the moment, I can't think of any logical reason.

However, in the first test, your aux pump should (eventually) come on and it doesn't. You say the pump will run (slowly) when you press a "raise" button. This tells me that the power supply to the pump is OK, and that the pump is correctly sensing low system air pressure. But it does not run in auto level mode. Why? To answer that question, you need the trouble shooting guide for your system. Do you have the user manual? Do you know what HWH series is fitted to your coach? If not, look here:

http://www.hwhcorp.com/ml17785_01_nom_pr_lesy.pdf (Scroll down - it's a long document)

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