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Topic: Air Tank Switch (Read 2072 times) previous topic - next topic

Air Tank Switch

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 –
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 –
Quote from: saddlesore –
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 –
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 –
Quote from: DavidS –
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 –
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 –
Quote from: Michelle –
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 –
Quote from: jcus –
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 –
Quote from: Michelle –
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 –
Quote from: jcus –
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 –
Quote from: Michelle –
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 –

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 –
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 –
Quote from: jcus –
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 –
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 –
Quote from: jcus –
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  :-X  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 –
Quote from: Michelle –
Yeah - I "assumed" the air schematic from our 2003 coach was correct  :-X  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 –
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 –
Quote from: propman –
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 –
Quote from: propman –
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.