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gweedo295 · 11-10-2021, 08:02 AM

Good morning, I am hoping someone in the know sees this right away. trying to leave on a trip with a large group.

this morning i started the rig to warm her up, came out to leave and i can hear air leaking under the dash. i shut it down the the air drops continuously. i move things around and i can hear an air change but don't what im looking for. im assuming its an air line, but what would it go to under the dash

Thanks.

Mudfrog · 11-10-2021, 09:53 AM

It's most likely a vacuum line or something in the hvac control itself. Since you say the sound changes when you move things around, it's probably a hole in one of the lines going into or out of the hvac assembly.

Does the hissing sound change or go away when you move the hvac controls to different settings? You'll just have to dive into it and listen with your ears to narrow things down. You can then replace the tubing or splice the damaged portion.

Edited to add: Looking at your signature, it looks like yours may be diesel? If so, I'm not familiar with the workings of hvac on a diesel rig and therefore can't say that my advice above will be of any help.

Argosy · 11-10-2021, 10:53 AM

Brakes, you probably don't have an air throttle, air pressure gauge. Do you have a cover over the left side of the instrument panel? Open it up, the air lines stand out from the wiring.

wolfe10 · 11-10-2021, 11:11 AM

The good news is that it is loud enough for you to find the source.

Start with checking these suspects: parking brake valve, air horn, air throttle if you have that style.

Unless you have an air driven vacuum generator, it will not be the HVAC vacuum system as they usually have a separate small 12 VDC vacuum unit (no connection to coach air system).

gweedo295 · 11-10-2021, 11:09 PM

Thnx for the replies, the air line was leaking at the fitting that connects it to the air gauge. I cut the line and reinserted it, it worked for about 25-miles, the line was too tight and wasn’t very straight. I put on two new fit ng and coupled new air line to the existing lines to allow for more flexibility.
T

RichKimball · 11-11-2021, 02:59 PM

Quote:

Originally Posted by gweedo295

Thnx for the replies, the air line was leaking at the fitting that connects it to the air gauge. I cut the line and reinserted it, it worked for about 25-miles, the line was too tight and wasn’t very straight. I put on two new fit ng and coupled new air line to the existing lines to allow for more flexibility.
T

Great news Gweedo! I had a line under the coach in front crack recently and was causing a leak. It was found easily and I cut it off flush and then re-inserted...only to have it still leak some. What I found was that on older coaches like ours...the o-rings inside the fitting also go bad. It's been said that the o-rings can be replaced...but FYI NAPA carries the needed fittings also.
I replaced the offender for $8. I need to pick up some couplers and some additional air line as mine are getting brittle and a little short.