Air hisses when Jack's lowered

[Jason Worman]

Hi All,

So we have the old hydraulic Jack's, I have wondered why they hiss air when they are lowered. They hiss for a bit and then quit. Anybody know why this happens? We do have the engine running when they are lowered. It is an old HWH System

Thank you;

Jason Worman

[Keith Moffett Co-Admin]

Hissing is likely the air ride being lowered.
Jacks often don’t have the length to level without lowering the coach first. 

[Fred Brooks]

   Jason,
The sequence of dumping the air bag suspension first is to get the coach as close to the ground as possible. Then when the jack leveling process is complete, the entry door and step are close to the ground. Fred

[Jason Worman]

There is a switch on the dash called the air dump override, should I use this with lowering?

[Steve Huber]

Why??
As Keith and Fred noted, air dump is normal to get coach as low as possible so jacks can make contact with ground.
Steve

[Jason Worman]

Steve,

The air bags are always inflated, is this normal? Just wondering, the owners manual does not talk much about the air ride system.

Thank you;

Jason

[Steve Huber]

Jason,
The air ride bags should deflate when you activate the jacks to level the coach (that is probably the air hissing sound you hear) and inflate when you go back to travel mode and lift the jacks. The earliest owners manual we have in CA is a 96 Monterey manual. Pg 42 covers leveling with jacks and states that one should run the engine for about 5 minutes to allow the bags to re-inflate prior to raising the jacks. Next time you level, have someone get out first and see if the coach settles when the air releases.
Steve