[Richard]

That is some huge leak.

The problem with internet problem solving is that you don’t know exactly how someone else has done something. I am surprised the inficon didn’t hear that. But I know I had to learn how to use it, which is quite different than the advertised instructions. I have the best results by using earbuds that go into my ear and block out outside noise. With a leak that big I would set the sensitivity at low. I would walk around the coach listening with the coach earbuds while sticking the snout inside every wheel opening and thoroughly in every bay. If I didn’t hear anything, I would crib the coach to keep it from sitting on me and scoot between the drive and tag tires to get under the rear. There are a lot of
Connections in that space. And lastly I would look carefully at the slide
Seals. If one of them is ruptured you can loose a lot of air quickly.

Please keep posting on what you do and what you find. This may help someone else in the future with a similar problem