Factory air system used as on board air?

[sag2]

I verified using 2020 3500 service info. It appears to be similar to the earlier models.

 

[dieselshadow]

Anyone confused yet?

 

[AH64ID]

I verified using 2020 3500 service info. It appears to be similar to the earlier models.

I've read some of the service info for earlier years and it doesn't describe how the 17-18 3500 systems work. I am not sure where the disconnect is, but I'm 110% certain I have an open system. The pump only fills the tank and then the tank fills the bags. When the truck lowers the air is expelled thru the intake, just like when it does a moisture purge with every start.

 

[dieselshadow]

But this purge, does it happen on every air equipped truck, every start? Surely I would’ve heard mine do it then? I have no faults. Truck rides great. Never heard the compressor run.

I mean it wasn’t all that long ago we went through all of this. I still came away with less understanding of how it’s supposed to operate. Just like now. Nothing solid, just different folks sharing what happens on their truck and their theory.

 

[dieselshadow]

I’m trying to understand how it works so I can even attempt to try and see if I have a fault or need to troubleshoot it. Right now I just know it’s there. And seems to work fine. Except there’s no noise....ever. LOL

 

[AH64ID]

But this purge, does it happen on every air equipped truck, every start? Surely I would’ve heard mine do it then? I have no faults. Truck rides great. Never heard the compressor run.

I mean it wasn’t all that long ago we went through all of this. I still came away with less understanding of how it’s supposed to operate. Just like now. Nothing solid, just different folks sharing what happens on their truck and their theory.

If you've never heard the compressor I'm not surprised you haven't heard the purge. I hear both semi-frequently, thou this time of year I am constantly changing loads.

Since dad's 2017 works the same I am pretty confident they are working as designed.

 

[sag2]

If they have a significant leak the compressor will overheat in short order and set an overheat code.

 

[dieselshadow]

If you've never heard the compressor I'm not surprised you haven't heard the purge. I hear both semi-frequently, thou this time of year I am constantly changing loads.

Since dad's 2017 works the same I am pretty confident they are working as designed.

From your description, it sounds like mine is dead.

Does anyone know a good way to test it out? Alt won’t work unless I load it up considerably. I currently don’t have anything to load it up with.

 

[Regcabguy]

I was thinking to fill tires mostly but no telling what they would do to my warranty if it failed.

They fill tires in Baja with A/C compressors on otherwise dilapidated trucks.

 

[AH64ID]

From your description, it sounds like mine is dead.

Does anyone know a good way to test it out? Alt won’t work unless I load it up considerably. I currently don’t have anything to load it up with.

I guess it's time to find an excuse to hook up to a trailer, maybe do some camping

But... you should be able to put it in transport mode, which will empty the bags. Weight in the bed does help too, but it won't take much.

Put it in transport mode and you should see it lower and hear, quietly, air venting at the "intake". Take it out of transport mode and you should see it rise.

Mine will often start to rise without the compressor running, but the compressor normally runs by the end to top the tank back off.

 

[AH64ID]

So I had to move the 5th wheel this morning.

Truck was still in ALT from parking the 5th wheel Sunday. It was riding at normal height but in ALT since I was empty and hadn't deactivated ALT yet.

So I backed the truck up under the 5th wheel and raised the landing gear. The weight pushes the truck back to ALT height and lower. I hear a valve open and air start moving into the airbags, no compressor. After about 1-2 seconds of bag inflation the compressor turns on. The truck stops adjusting and the compressor ran for about 5 seconds after it was done adjusting the height.

So then I unhook. As I lower the landing gear the truck comes up with the 5th wheel, then it releases air from the bags. No compressor, just air venting from the "intake". It does this a couple times as I remove all the 5th wheel weight. The compressor didn't run at all while unhooking.

Back in the truck I turn off ALT and nothing happens since I was already at minimum pressure and normal height.

So that's how it works on my 2018. Each time I started the truck I also heard the compressor/tank purge.

I know it feels like a dead horse, but there is still a lot of confusion (thanks FCA) on this system.

Maybe this winter when I load a ton of pellets in the bed I'll try to get a video of it adjusting.

 

[EZeis]

So I had to move the 5th wheel this morning.

Truck was still in ALT from parking the 5th wheel Sunday. It was riding at normal height but in ALT since I was empty and hadn't deactivated ALT yet.

So I backed the truck up under the 5th wheel and raised the landing gear. The weight pushes the truck back to ALT height and lower. I hear a valve open and air start moving into the airbags, no compressor. After about 1-2 seconds of bag inflation the compressor turns on. The truck stops adjusting and the compressor ran for about 5 seconds after it was done adjusting the height.

So then I unhook. As I lower the landing gear the truck comes up with the 5th wheel, then it releases air from the bags. No compressor, just air venting from the "intake". It does this a couple times as I remove all the 5th wheel weight. The compressor didn't run at all while unhooking.

Back in the truck I turn off ALT and nothing happens since I was already at minimum pressure and normal height.

So that's how it works on my 2018. Each time I started the truck I also heard the compressor/tank purge.

I know it feels like a dead horse, but there is still a lot of confusion (thanks FCA) on this system.

Maybe this winter when I load a ton of pellets in the bed I'll try to get a video of it adjusting.

That's how my 18 3500 SRW works. No sealed nitrogen system. A compressor system that runs the compressor and purges air for the bags and does a purge at shortly after start up. I believe some have no idea how their system works and just says it's a sealed nitrogen system cause they heard or told that. Does a sealed nitrogen system exist? No sure, I have my doubts as it would eventually need recharged due to leaks and the nitrogen passing through the bags.


Earl

 

[sag2]

Having not personally worked on an 18 I can only go by what the FSM says, and that is it is a sealed system. But based on good descriptions from you guys it appears the system does vent to the atmosphere. What would be a good test is to have someone (AH64ID) pinch off the air filter line and see if it still vents following the same procedure.
I worked on a bunch of Jeep and 1500 systems before I retired and I'm positive they are sealed systems.

 

[AH64ID]

Having not personally worked on an 18 I can only go by what the FSM says, and that is it is a sealed system. But based on good descriptions from you guys it appears the system does vent to the atmosphere. What would be a good test is to have someone (AH64ID) pinch off the air filter line and see if it still vents following the same procedure.
I worked on a bunch of Jeep and 1500 systems before I retired and I'm positive they are sealed systems.

I’ll keep that in mind.

I was around a 1500 with the system last month. I didn’t get to mess with it much, but it did act more like a closed system. So I guessing most the sealed info is describing the 1500, but inaccurately used for all platforms.

 

[Cummins12V98]

I like that mine stays in the lower ride height no matter loaded or not. That is a biggie to me!

 

[AH64ID]

I like that mine stays in the lower ride height no matter loaded or not. That is a biggie to me!

Just means you have more weight in your bed than the rest of us, or the springs were softer in 15. We know they changed the overloads some since 15 too.

 

[Ozymandias]

One could check on techauthority.com if he really wants to know what's in his vehicle.
Sure there are different types for 1500/2500/3500 and Duallys.

 

[sag2]

One could check on techauthority.com if he really wants to know what's in his vehicle.
Sure there are different types for 1500/2500/3500 and Duallys.

That's where I checked.

 

[Ozymandias]

That's where I checked.

Did you see differences for my mentioned types and models?
Especially 3500 SRW/DRW?

 

[sag2]

No difference between models as I didn't use a VIN, just YME.