There seems to be a lot of discussion here about just how long the aux compressor should run. We have been monitoring ours. My dash gauges show over 100 pounds. This morning, I heard the compressor come on with 100 pounds, but ran for over 1/2 hour. We recently spent a small fortune at MOT fixing leaks and rebuilding six packs, so I don't think it's a leak....but not sure.
A good friend of mine, and fellow Foretravel owner, told me to turn off the HWH, and that that would shut off the compressor. It did NOT.
I was told that it would shut off at 90 #. Then why did it call for it to come on, with plenty of air and no yellow lights on?
Although I have read different info here, I turn off my aux compressor, fire up the engine, build up pressure to over 100#, and level or relevel the coach. That's how I have been doing it for years. I have had both MOT AND HWH try and remedy this issue, with no success.
Any ideas??
Thanks
What HWH Leveling System do you have on your coach?
680 like mine I would suspect
Glenn,
I can sense your frustration. I'm not an expert but here are some observations on my coach. It may help you understand yours.
I have 4 tanks.
The dash gauges show the pressure in the front and rear brake tanks. The tanks are mounted near the front axle.
There is also the wet tank mounted near the rear axle that feeds the brake tanks. No gauge for it oem.
There is a HWH tank in front of the front axle. It is fed from the 12V compressor. No gauge for this tank oem.
When parked, The compressor feeds the HWH tank which feeds the level system and the slide bladders. A leak anywhere in the system will eventually cause the compressor to run if the leveling is turned on. If the level is turned off, a leak in the bladder system will cause the compressor to run.
My compressor never runs for 30 minutes. It may run about 10 minutes to get the coach to full height to install the safety stands. It may run once or twice a day for 3-4 minutes to keep the tank full. I have not heard it run since we got here on Wednesday but we have not been home the entire time. It has run more frequently in the past (4-6 times a day) but my system is currently pretty tight.
The air schematic is very interesting reading.
I don't know why the compressor would run for 30 minutes but I would start by installing a gauge on the tank. One easy place to do that on my coach is on the line from the HWH tank to the slide manifold where it attaches to the manifold. It is easy to access to install and read. I was able to monitor tank pressure and compressor performance.
There is a shutoff valve for the slide manifold. You can use it to start isolating parts of the system to look for leaks.
You should not need to start your engine to level your coach. The 12V compressor and HWH should do that.
Hope this helps your understanding and exploration of the problem.
Rich
Out of curiosity, I downloaded the operator's manual for the HWH 680 Series. .pdf link below.
Page MP85.473E in the manual describes the "normal" operation of the aux pump on this system.
The way I understand it, there are two operation modes. One is the automatic mode, which is triggered by a "raise" request from the HWH control box in automatic or manual leveling. In this mode the aux compressor will pressurize the leveling system to 110 psi (controlled by a Relief Valve) and will run as long as the "Raise" request is active.
The second mode is triggered when the operator turns on the Auxiliary Air manual switch. In this mode the aux compressor pressure output is controlled by the Pressure Switch which opens (turns compressor off) at 90 psi and closes (turns compressor on) at 60 psi. Output from the pump goes directly into the air system at some point - where exactly I'm not clear on. Wet tank?
It looks to me like there is no actual time limit on how long the aux compressor will run in either mode.
Glenns problem is that the aux pump runs with the HWH system "off". When he ran the engine and air built up to over 100 lbs it shut off. He shut the engine off and the pump did not come back on for 2 days and then it came on and ran and ran without being out of level. It was adding air to the tanks but at what point (or time) does the aux pump stop? Rich Bowman's post is excellent in that he says it will come on frequently to keep air in the tanks. How much air? I'm thinking there is no problem and the pump will shut off at a certain poundage of pressure. He is hesitant to let it run too long. It does not get hot.
Glenn,
On my coach, there is one more way the 12V compressor may run. I have an AIR TANK switch on my drivers side panel. This is meant to turn on the compressor and fill the wet tank. If that switch is on, it is very possible that the compressor could run 30 minutes. The wet tank is much larger than the HWH tank and would take longer to fill it and the two brake tanks it feeds.
This was added by FT to allow you to get the brake tanks up to pressure before starting the engine. This would allow you to leave camp quicker and quieter than starting the engine and allowing the tanks to build air pressure. Most, including me, agree that it is not worth the effort. I never turn it on.
Rich
Failing pressure switch maybe?
The way I understand it Rich when the tank switch is turned on it opens a solenoid on the line to the brake tanks, dropping the pressure on the compressor line and pressure switch is telling the compressor come on.
It may be that the teflon rings in the aux air compressor are worn and air won't be compressed to cut out pressure, and so it continues to run trying to reach set point.
The air pressure is adjustable. I have mine set for 75 PUS.
This is the pressure switch component.
Square D by Schneider Electric 9013FHG2J27 Air-Compressor Pressure Switch,... (https://www.amazon.com/gp/product/B000CCJ6QK/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1)
More on the adjustable pressure switch:
Aux 12 volt compressor compartment "thumping" sound (actually air unloader) (https://www.foreforums.com/index.php?topic=34259.msg314643#msg314643)
This morning, I am out of level and the coach is low to the ground. The red light is "on". The two gauges are reading "empty"
I will try and bring the coach up to level. I now fear I may, indeed have a leak, and will start an inspection.
It has been mentioned that there is a shut off valve for the slide manifold but I have not identified it. Any help, maybe a picture??
I ran the aux compressor and it does NOT level my coach. I will have to fire up the engine.
How do you set limits in the pressure switch?
Thanks
OK. This is a "first"I just ran the engine. Pressure on left gauge came up to 125# right 115#. The bell was dinging and the level light was on They USUALLY stop dinging and the light comes off when the green TRAVEL light comes on.
THEY DID NOT ???!!!!
I am level and holding pressure, for now, BUT now I am concerned about being able to put it in gear.
Any suggestions are welcome.
I stuck my head under the coach to listen for air, but heard nothing.
We just fired up the engine. The level light and dinging were going strong. Put it in drive and reverse, it engaged, BUT kept dinging with the level light on.
Level light and dinging probably means the HWH system pressure switch does not "know" that the air pressure is above 80 psi.. The switch is located on the rear 6-pack manifold. You could check the wiring going to the switch for damage, and if it looks OK try unplugging the connector and plugging back in.
When you unplug the pressure switch connector, check up front to see if the dinging stops. The pressure switch is NC (normally closed) and opens when system pressure is above 80 psi. Unplugging the connector should look to the HWH control box like switch is open (pressure > 80).
Tap on the pressure switch to get it unstuck.
If that resolves it you know which one to proactively replace. I would probably order a pair and change them both. Safety stands in place.
Scott
AFAIK, there is only one 80 psi switch on the rear manifold. There are two 10 psi switches on the front manifold.
Tap on the pressure switch???
Sorry....NO idea of where that is
I am pretty concerned about this and could use specific guidance. Thanks
When you say "Level Light," I assume you mean the one on the front dash. It should probably really say "HWH," because it will come on for problems with the level system or the slide room. It will come on if the coach is not in travel mode or the room is not in completely. On mine, I had a problem for awhile when driving and hitting a big bump. The room in sensor would jiggle and think the room was not in. I would have to stop and extend/retract the room to clear it. I was able to reseat the sensor and fixed the problem.
If that light was on, you should not have been able to go into gear. It is possible that your override switch is already turned on. Mine was when I bought the coach and I didn't figure that out for awhile. It would be worth checking. Don't know where your switch is located or what it looks like. Someone with your year and model may be able to help.
My slide manifold is located in the #3 bay, right wall on the driver's side. The valve is right where the air supply line is connected to the manifold. If you turn it off, your bladder will not deflate/inflate. It must be turned back on to extend/retract the slide or you risk damage to the bladder.
Rich
Glenn,
Can't help with the pressure switch question. Your HWH manual should have some good system info and trouble shooting tips. I think they are available on the HWH website.
Each year/model coach is a little different so I'm able to supply general info but not coach specific on the HWH systems.
Sorry I can't be more help.
Rich
On the road - level system alarm intermittent, travel light intermittent (https://www.foreforums.com/index.php?topic=43369.msg439892#msg439892)
85 psi switch on rear six pack:
Description: switch, pressure manifold.
HWH part RAP15387.
On the switch: NASON SM-2B-85R/WL290 .
Don't crawl under the coach to check it out while depending on only the air bags.
Install safety blocks at go to six pack and tap on the pressure switches next to the control solenoids. Or just the side of the six pack will probably be enough. If they are just stuck they will switch over till the pressure is low again. Probably stick again
I think the pressure switch is on the rear 6 pack, I replaced it on my 2000
Keith
The level system light and dinging will be on if the system does not sense that the slide is in and pins are engaged. Check the box on the ceiling in your main bay on the drivers side. Lights indicate which are locked or not.
Your dinger is easy to find on the driver's side under the hump. Add an on/off switch.
If you can put it in gear then the override switch in the HWH cake pan next to the indicator light panel it probably switched.
Thanks for the response. I think we're ok
So... what did you do to fix the problem?
We are still not sure why the aux compressor comes on, but seems to not shut off.
The dinging and dash light was because I had the slide out. HDF. High dummy factor. Just wasn't thinking clearly.
My aux compressor airs from low pressure 60 psi cut on to 90 psi cut off in 3 minutes 30 seconds. Any longer and I have a leak.
2001 U320 one slide