This is probably nothing to worry about, but I'll put it our there as I've never seen it before. We parked, cut the engine got all set up and settled in. About 25 minutes after shutting off the engine, I was outside and heard what sounded like a slow pressure build then then the air dryer purge valve popped off but with much less force than when the engine is running. Can't hear any leaks since, coach is holding pressure, and don't see anything that looks out of place under the coach. Keith did the regular air dryer service a couple month ago.
Anyone seen this before and should I be concerned?
Joe, are you sure it was the air dryer purging ? Did you have the Auto-Level set ? It might have been the Level System coming on and leveling the coach by draining some air from an air bag. It gives that same swoosh sound of air, just not quite as loud as the dryer. Maybe??
Mine does that for as long as I can remember. Usually about 5-10 min after shutdown.
+1, especially with the roughly 25 minutes (let's call it 30) after engine shutdown. That would correspond to the first wakeup cycle of the leveling system to check for level, and it's not unusual for some settling to have occurred as things cool down from the drive.
Definitely not the auto-level. I know that sound. It could have been something other than the air dryer, but the force was enough to blow some dust.
Our GV does the same thing.
Wonder if there's a check valve in the system that's leaking back and over-pressuring the air dryer relief valve?
The auto-level is an instantaneous dump of air, and it a typically a different sound. We auto-level a lot and I've never seen it blow dust.. The lead-up sound then dump similar to the air dryer makes me pretty certain its not auto-level
I'm thinking settling is a good diagnosis, maybe back pressure from the airbags. Or maybe it way just right on the edge when we shut down and the settling in caused it to pop.
On your age coach along with the others in this thread this is possible.
On the dryer if it has the isolation valve there should be a 1/4" line that comes off and heads to the front. It may be tagged 60. This line terminates on the wet tank with a 90^ fitting. That 90 should be a check valve. Hard to get to, hard to find, YES If the coach has this system and that check valve leaks will it cause these symptoms? Yes
Mike
Flatulence!
Along the lines of what Michelle said. 10 or 15 min after shutdown I will hear an air wonderment and it will do it once and it isn't purge. Some things we may never know the technical answer to but I wouldn't be concerned.
Could also be heat soak (dryer in engine bay)-- rise in temperature> rise in PSI. Rise in PSI could exceed cut-out PSI.