[Land Yacht]

I drove my coach today just to exercise it and make sure all systems are go as we near the Bella Terra no-rally rally. When I stopped I could hear a big air leak in the front near the compressor. After I parked it back in the warehouse and leveled it. I went to investigate further. I could still hear the leak but was less pronounced than before. As I investigated further the leak lessened, I am guessing it is because the pressure was lower. I squirted joy soap and water from a sprayer but could not find bubbles to my surprise. Is there a better mixture for finding leaks?

I think it is coming from the drain solenoid (not sure what it is called but picture below). This will be my first air leak fix, and open to any and all suggestions. Do I need special tools or parts to make it easier and more realizable? Thanks Mike