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Proper air pressure in holding tanks

December 10, 2013, 03:02:58 pm

I have looked in archives and cannot find a definitive answer. 01 U320.  I always have different air pressure readings in front and rear holding tanks. Factory said they were normal, but no explanation of why the variance. Can someone explain why so much fluctuation?  Front tanks vary from 75-90. Rear usually in the 100-110 range. I keep wanting to suspect a bad gauge.

Should the tanks be equal in pressure?

Thanks,

David

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Re: Proper air pressure in holding tanks

Reply #1 – December 10, 2013, 03:35:31 pm

Simple thing might be to swap your gauges and see if they show a reverse of what you have seen.  Other idea is to install a gauge on the tank drain and see what your pressure is with a new and different 3rd gauge.  There was a recent thread with differences on dash gauges, but the rear seemed to be the lower number.

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Re: Proper air pressure in holding tanks

Reply #2 – December 10, 2013, 06:04:21 pm

And if after changing guages you get the same readings as before then take off the check valve on the lowest tank and see if the seat is good. Maybe you too have a bad check valve there
John H

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Re: Proper air pressure in holding tanks

Reply #3 – December 11, 2013, 01:10:55 am

David, we have the same model/year coaches.  Had similar problem.  Turned out to be a bad gauge.  Problem to replace, no SW replacement was said available, so went to mechanical gauge.  Only issue now is a false chime alarms that pressure at time, the sensor is no longer getting the electric signal. 

I am told we can fix that by disconnecting the chime but would lose it for all areas.  In other words, I would no longer have the chime for the system sensing some other urgent problem or need, so I leave the false chime.  Not the best having that but got used to it.

Hope this helps.

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Re: Proper air pressure in holding tanks

Reply #4 – December 11, 2013, 05:37:28 am

David, could be a bad guage, also looks like you air governor may set a little low, should be set for cut in at 100 psi and off at 120-125 psi. Both of mine read the same pressure about all the time. As others have said change the lines around on the guages and see what happends.

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Re: Proper air pressure in holding tanks

Reply #5 – December 11, 2013, 12:23:45 pm

Thanks to everyone. Will embark on trying different options and report back.

David

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