Just joined the forum so I could help shed some light on this old, but seemingly revived thread...
First - if you're DIYing this system (which you probably should because even most master techs at dealerships don't bother to understand it), you HAVE to have a *quality* bi-directional scan tool. Don't even LOOK at a component of this system without one. I personally just use the AlphaOBD app on my (Android) phone and an OBDLink MX+ adapter. This $50(?) app has undoubtedly saved me MANY thousands of dollars over the 3 years I've had my Ram.
Second - You guys that are worried about the purge noises - you should be worried, but for a different reason. This 'short purge' is normal, but only after each time the system is commanded to bring in supplemental (ambient) air. The reason the system does this short purge is in order to dry/clean out the desiccant can that's attached to the end of the inlet hose (behind your tail light). So, if you're hearing this purge regularly, it's a sure sign that you have a leak somewhere. Soapy water spray-downs with a fully pressurized system are necessary. The spray-downs of the air bladders need to be observed at all different ride height selections (and ideally *while* adjusting) in order to give you accurate results (see next point).
Third - Air bladder/bag leaks - These will often *seem* intermittent / difficult to identify. This is because the bladders roll/fold over themselves to differing extents throughout their range of motion. The way these leak are via small holes/cracks that develop over time. When minor, these are able to "self-seal" to some degree *when positioned favorably*, but when they get positioned in such a way that they are on the 'edge' of the 'rollover' (my own terminology here), they become un-sealed due to the extra stress on that area of the bladder. This causes air/nitrogen loss. These cracks/holes typically develop on the bladder where the rollover is most often located - say, 'normal' ride height, for example. So when the bladder is at this "normal" height the cracks are exposed/stressed, and leak. But if you change the ride height to 'aero' or 'offroad' or 'entry/exit', this changes where the rollover is on the bladder and oftentimes puts the cracks back on 'the flat' of the bladder where they manage to seal themselves back up. This is where the "intermittent" thing comes in. The holes/cracks are always there, but they may not actually leak unless they are positioned on this rollover edge. This is why you might park it overnight at "normal" height and find, say, your rear driver's corner an inch or two lower in the morning; but not ALL the air is gone. What happened was the cracks leaked until they were no longer on the rollover edge, then were able to seal up. When you turn the vehicle back on, the ASCM will send air from the reservoir to the leaking bag to replenish the lost air and get back to the commanded height, and then may trigger opening of the supplemental ambient air intake in order to then replenish the reservoir. This introduces moisture which can wreak havoc in freezing temperatures, etc. Now this cycle repeats itself until the cracks become worse, leak more, and eventually start to stress your compressor, etc - blowing the 40A compressor fuse, getting overheating errors and other malfunction lights, and getting all kinds of wonky and inconsistent ride heights from all 4 corners. The malfunction messages/lights and even DTCs will have you pointed in a million wrong directions and you'll find yourself throwing thousands of dollars worth of unnecessary parts at it if you don't simply diagnose and address the leaks first.
I could keep going, but I think this is getting a little long-winded. One last thing I'll mention: Air still moves within the system even if your compressor is shot/fuse is blown, so a leaky *rear* bag can sometimes present itself with a *front* corner (or both) dropping to the bump stops while the rear still appears ok (or sometimes even over-inflated). This is because the valve block is still allowing movement even though the compressor isn't there to help. This will obviously cause issues when the ASCM wants to move air from a component (ie: a bladder) with *less* pressure than its destination (ie: the reservoir), as there's nothing working to overcome the pressure differential (ie: the compressor).
Happy to help further if anyone has questions.
