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Topic: 03 U295 12 V compressor running constantly (Read 1101 times) previous topic - next topic

03 U295 12 V compressor running constantly

I have a '03 that I bought back in Sept at MOT. I have it parked here in S Calif. on a level pad. I go down and check it every week. On today's check I found that the 12 v compressor was running constantly. I store the unit in travel mode, so I did a level, everything worked fine, but  compressor was still running. I went back to travel mode and compressor still running. I finally pulled the 5 amp fuse to shut the thing off. The unit has been stored with the slide in and has not had the slide out in a month. Could the bladder seal be causing the pump to run?

Thanks,
rick

Re: 03 U295 12 V compressor running constantly

Reply #1 –
Quote from: rickandteresa08 –
I finally pulled the 5 amp fuse to shut the thing off. The unit has been stored with the slide in and has not had the slide out in a month. Could the bladder seal be causing the pump to run?

Possible - but listen around the slides to see if you can hear air leaking.  In our experience it's easily detectable when the slide bladder is leaking.

In our 11-year ownership experience, the most likely causes of continuous aux compressor running are the relief valve on the bottom of the clear bowl in the area of the HWH compressor (it should seal when the pump is running - check for air leaking there) and also the bowls themselves (we replaced ours in 2011 due to cracks that were leaking pretty badly; in particular check the fitting at the bottom of the clear condensation bowl where the pressure relief valve is attached).

The pressure relief valve is the thing that goes "pshewwwww" when the aux compressor stops running and it makes that noise as it opens to purge moisture/condensation and unload the pressure from the compressor.

Re: 03 U295 12 V compressor running constantly

Reply #2 –
I would suggest leaving the pump off (switch off/fuse pulled) while it is stored.  If you have a leak and the pump runs for days it will likely wear the pump out or run the batteries down. It only takes 15 psi to inflate the seals so they will be tha last thing to go flat.

Hunt down the leaks and get them fixed.  No easy way to say that other than it nneds to get done.  And then there will be another leak down the road.  In addition to what Michelle suggests make sure your tank drain valves are actually closed.  I am also strting to replace check valves that are leaking back.

Michelle ... Doesn't the 2003 have a switch for the pump on the side panel next to the driver?  Does this turn off the pump?  Or just force it to come on.  It also seems to me that the 2003 plumbing includes the wet tanks as well as the HWH tank.  They have a bigger pump than the 2001 and the plumbing is different.

Here is the 2002-2003 air system schematic (with tag axle). Without a tag is the same without the tag parts.  Thanks Barry.

Re: 03 U295 12 V compressor running constantly

Reply #3 –
Quote from: Roger & Susan in Home2 –

Michelle ... Doesn't the 2003 have a switch for the pump on the side panel next to the driver?  Does this turn off the pump?  Or just force it to come on. 

The Air Tank switch on the panel links the aux compressor to the A and B chassis tanks to help air up for travel (akin to the Boost switch linking the house batteries to the engine batteries to help starting).  It should be off 99% of the time and ONLY used if you want to air up the A & B brake tanks without running the Cummins.  Not enough desiccant charge to recommend doing this regularly.

Pulling the inline aux compressor fuse will stop the aux compressor from coming on if the bladders are calling for it due to a leak or if there's a leak in the bowls.  If the leveling system is left on the aux compressor will come on to try and level the coach (unless it times out, in which case it will throw an "excess slope" light on the HWH main panel.)

Our routine storage practice (since we can't store at this house) is to level the coach on the lower end of height, shut off the leveling and pull the fuse. 

Re: 03 U295 12 V compressor running constantly

Reply #4 –
Rick, I agree with Michelle, check desiccant bowl and surrounding air lines for leaks. Also around your slides, if you have a leak there you will hear it. BTW, what part of southern Cal are you in? We're in San Diego.

Re: 03 U295 12 V compressor running constantly

Reply #5 –

    I had a leak in the drain valve for the 12v compressor line and it was running constantly also.
    Check the 3 drain valves located on the drivers side forward of the front tire.

Re: 03 U295 12 V compressor running constantly

Reply #6 –
I got tired of pulling the fuse so I ran a fused wire loop from the pump +12v power to the side panel to the left of the driver and added a switch to turn the pump on or off and then back to the pump.  Beats crawling around in the basement.

Re: 03 U295 12 V compressor running constantly

Reply #7 –
Quote from: Roger & Susan in Home2 –
I got tired of pulling the fuse so I ran a fused wire loop from the pump +12v power to the side panel to the left of the driver and added a switch to turn the pump on or off and then back to the pump.  Beats crawling around in the basement.

Roger, good idea.

But even better if you install a relay next to the compressor and only run the signal wire up to a convenient location.  That leaves more voltage at the compressor.

Let me now how yours is wired now, and I can post a "how to".  Basic issue is whether you already have a relay at the compressor AND, whether compressor positive to power the pump goes through the pressure switch or the pressure switch is just used to close an existing relay.



Re: 03 U295 12 V compressor running constantly

Reply #8 –
Hi Brett,
Here is what I did.  I cut  the red wire (+12 v) running from the relay to the compressor motor, added a 15 amp fuse, ran 10 ga wire up to the panel on the driver's left side, put a switch in and the 10 ga wire back to the red wire to the compressor.

Option 1 would work too as that would cut power to the valve on the bottom of the water catch bowl.  That valve is always on (open). 

Option 2 would have interrupted the relay switched ground side of the compressor.

Option 3 would have been a low power option interrupting the +12 v signal from the pressure switch to the relay.

I like the option 1 now that I look at it.  That valve at the bottom of the bowl is always powered, enough so that it is quite warm to the touch.

Adding in another relay would be ok as well.  So far it seems to be working fine (> 1 year)

Re: 03 U295 12 V compressor running constantly

Reply #9 –
Roger,

Sorry, the schematic is difficult to make out on my small screen.

But, based on your descriptions, I lean toward: Option 3 would have been a low power option interrupting the +12 v signal from the pressure switch to the relay.

Signal wires carry very little current (just enough to close the relay)/are not affected nearly as much by long wire runs as are wires carrying a lot of current (i.e. to run the compressor).

Basically, interrupting the "turn on signal" from the pressure switch would be worth a look.

Re: 03 U295 12 V compressor running constantly

Reply #10 –
Thanks Brett,  it is easy to connect differently at this point.  I have a few of the black Bosch 30 amp relays and wired sockets.  Interupting the power to the whole compressor shuts off the continuous load from the bowl valve. Another parasitic load that is not needed.

Re: 03 U295 12 V compressor running constantly

Reply #11 –
Thanks for all the great responses. Turns out the pressure relief valve was/is sticking open. Couple of taps with a screwdriver and it sealed right up. Pumped up the tank to 100 psi and pulled the fuse in case of future sticking, plan on doing the on/off switch mod soon. Anybody know the part number for that pressure relief valve?

We are located at Jojoba hills skp park just south of Temecula. Got two other Foretravels here so I have some on site help if needed.

Rick

Re: 03 U295 12 V compressor running constantly

Reply #12 –
Good find. Listening/feeling for the leak is a good place to start. 

Susan always reminds me to start at the beginning, try the basic and obvious things first. Don't over complicate it. She brings the common sense out every time we open the tool box. 

Re: 03 U295 12 V compressor running constantly

Reply #13 –
Hmmm... I just put a toggle switch in line with the fuse. Not very elegant, but works. Just have to go to the basement to use it.
Dick

Re: 03 U295 12 V compressor running constantly

Reply #14 –
[quote author=Roger & Susan in Home2 link=msg=219600 date=1450064641 Susan always reminds me to start at the beginning, try the basic and obvious things first. Don't over complicate it. She brings the common sense out every time we open the tool box.  [/quote]
 
My employees would do the same thing on a service call; they'd go to the "dark side", and when "Dad" would have to come over to the site, he'd find a simple fix! They hated me, but sometimes a fresh outlook furthers!
 

Re: 03 U295 12 V compressor running constantly

Reply #15 –
Rick, reported elsewhere this experience.

Installed a pressure gauge so I could read the air pressure in the air tank supplied by the aux compressor.  Via monitors that gauge, I learned how quickly the aux had to come on to air the tank.  About every three days.  I found that leak was from a shut off valve that sends air to the slide bladder from the tank system.  That isolation is important, for me.

That led to, why was it talking so long for the aux to bring the third tank to full pressure? It was unrelated to the leak down rate.  Usually full pressure was reached in 3.75 minutes, and that had become 14 minutes or more.  Found that was due to a crack in the plastic bowl, replaced that and the time to cycle dropped back to the less than four minutes. 

(I had already installed the switch per Dick S.)  Glad yours is working good now, but our lessons about the same.  By the way, I leave the coach in travel (off, not level mode) when parked for weeks at home, and I have now found it will sit for a week or more without activating the aux.  My main tanks do not leak down below 75 psi within three weeks but this unrelated to the aux compressor but is indicative of the progress on finding leaks.