2001 Chevy Silverado. I had the hood open yesterday and noticed oil on the line in the first photo. It seemed to be coming from the valve under the nearest black cap. I took off the cap today after a drive and saw clear oil bubbling out of the valve. The liquid puddled on the inner fender in photo 2 is condensation, but a little oil seems to have gotten down there as well. The A/C system has never been worked on, and I haven't noticed any recent changes in cooling performance (yet). I have three questions: First, what is this part called? Second, can I fix it with a new part and a wrench, or will the refrigerant leak out? In that case, I would need to take it to somebody with the right equipment. If it comes to that, what will the job include? Thanks in advance--a lot of you have a lot more experience and know-how with A/C than I do.