93 Vectra

Wild guess, but air inlet for the compressor?

With out further information or a picture, my best guess is, it is the fresh/clean air supply for the air compressor. Needs to be repaired ASAP! You are loosing boost pressure and getting dirty air into the compressor, both bad news.

Yea I think you are right. And that answers other problems I have been having.

THE ISSUE I have is whose bright idea was this this and why can/t I find info on it.

Doesn't matter I think you guys are right.

Addendum: It actualy is a good idea. It doesn't require another air filter and the loss of boost is probably miner.

Yea I'm going with that and just wish more info was available on these industrial engines in RVs.

You don't mention what engine you have, but suspect a Cummins B 5.9 liter diesel. Lots of owners here with that engine.

Very widely used engine. And, if the hose from intake manifold to air compressor is missing/broken, you should have a SIGNIFICANT loss of boost.

Boost control is vacuum and obviously the turbo is not seeing vacuum levels. On top of that vacuum is compromised.

eHoefler wrote:
With out further information or a picture, my best guess is, it is the fresh/clean air supply for the air compressor. Needs to be repaired ASAP! You are loosing boost pressure and getting dirty air into the compressor, both bad news.

Yes it is a Cummins 5.9 6BT.

Yes a broken hose will cause "significant" loss of boost.

I was questioning if anyone knew specifically about this connection and what is it for.

I think eHoefler nailed it that it was an easy way to get clean air for the compressor. I found it by accident and wanted to find more inf0 on it.

I thank you all for your imput. I feel more comfortable now that I believe I understand what/why it is there.

Yes, very common for the air compressor to receive air from the intake manifold.

It is already filtered (main engine air filter), pressure raised by the turbo and cooled off by the CAC. Much better than any other option for supplying it with air.