The leak was at the compressor. I could find the air line, it was no longer attached to anything, but it tight in there, compressor and governor are between the frame and the block. I could not see what the line was hooked up to. The mobile guy climbed under, asked me if I wanted to come take a peek. I crawled under and he showed me where it went, and why it failed. Unfortunately it broke the fitting, he replaced it with a brass one, said I will never have a leak from there again. He had to reroute another hose that was rubbing against the air line fitting and blocked the view when I tried to see where it went, caused the failure.