Loud leaking air sound

[Johnek]

Was driving along at highway speed when I heard a loud pop and what sounded like air escaping. I pulled over and quickly found that the air sound was coming from a small hole on the front of a small rectangular box mounted on the firewall near the drivers side. It had a line attached to the top of it coming from a spherical black ball like unit also mounted on the firewall. My brakes were not affected however it did take much longer to build up air pressure so that I could release the parking brake. Once underway, as long as the RPMs were above idle, the low air pressure light stayed off. The hissing was still there however. I haven't a clue what the items on the firewall are or what they do. Any help is appreciated. TIA.

[Skip426]

If your low air warning is on your very close to the brakes being effected .
Maybe even being stopped on the road if the park brake comes back on .

Have to ask what chassis your coach is built on ?
And can you take and post pictures ?

Info on posting photos in this link.

http://www.irv2.com/forums/f62/forum...ics-49134.html

[RealNiceTent]

As hard as I tried not to say it Skip, some people are just blessed!

[CountryB]

What you describe sounds like the "vacuum pump" which is used to make vacuum for controlling the dash AC/vent doors. The round plastic (sometimes coffee can shaped) thing is the vacuum reservoir.