Seneca Air brakes question

[Dchafe]

Hi all, we just had our Blue Ox, Airforce One unit put in for towing our Jeep. When I parked the Seneca the air pressure gauges were showing just under 150 psi. It’s been parked for about a week now. The gauges are now showing about 100 psi. Is it normal to lose pressure while parked? I just making sure since the new install. New to the air brake system. Thank in advance for replies.

[Grumpy]

Typical of most air brake systems.

[Robbbyr]

Originally Posted by Grumpy

Typical of most air brake systems.

X 2 what Grumpy said. If it dropped that much in a few hours that would be excessive, but not for a week.

[Mnwelsh]

You will also notice as you cruise down the interstate the pressure will drop, sometime there will be different pressures with one system quite a bit lower that the other. This is normal. When it gets low enough you will hear the ticking sound from the air pump and they will build back up to max pressure at which point the air dryer lets air out with a sound I can’t spell and the pump shuts off. All of that is normal.

[Dchafe]

Thanks for the info! I did notice the air pressure dropping on the way home from getting the towing system installed. At one point, they both came from about 110psi to 150 quickly.

[McGintys924]

Does the Seneca use air for other items such as shifting? Does the suspension give and take air as it travels down the road? As for your Air Force, I would think some soapy water over any newly installed connections could assist in evaluating leaks.

One thing is that Jayco discovered and replaced a cracking elbow right out of my air pump after two years of use.

[Robbbyr]

Originally Posted by McGintys924

Does the Seneca use air for other items such as shifting? Does the suspension give and take air as it travels down the road? As for your Air Force, I would think some soapy water over any newly installed connections could assist in evaluating leaks.

One thing is that Jayco discovered and replaced a cracking elbow right out of my air pump after two years of use.

Senecas use air to control the engine cooling fan, so hotter temps will cause it to engage more often but that is a miniscule amount of air. The Allison transmissions we have do not utilize any air for shifting.
Just driving down a bumpy road will cause air to release and then be replaced in the rear air springs. Air is also applied and released as the air brakes (if so equipped, my Seneca is not) are used while driving. So tank pressures will fluctuate at times since the engine-mounted air compressor isn't continuously pumping air into the system. Yes it is being driven by the engine constantly, but it has a governor/unloader control system that "cuts-in" and "cuts-out" the actual pumping of air at defined pressure points.

[EA37TS]

It is my limited experience of 3 trips with the 2020 Accolade that the secondary tank will loose air pressure more that the primary tank. Apparently the air suspension uses the secondary tank (evidenced by pressure drop during leveling) and as you travel down the. road air is released and applied to the air springs. The air brakes primarily use the primary tank and this can be observed by applying and releasing the brakes.

Which tank/system did they tie the Air Force One into, primary or secondary? If they tied into the secondary you could see a higher than normal lose of air due to the air suspension and toad brakes while traveling down the road.

Also, as a note, when my coach his parked and leveled the secondary will bleed down quick due to air being released when leveling but the. primary takes a number of days (haven't observed to record the exact number) to drop below 150 or 120 PSI.

[Dchafe]

Really good info and questions to ask on which tank line they tied into. Is either one ok to tie into? I also didn’t realize what was connected to the air system.