This is an anger vent. Two weeks or so ago my friend took his car to an oil change place and bought the "$65 synthetic oil change". Today he turned on his AC and it wouldn't work. Short story: Met his auto mechanic friend -with manifold- at Walmart and recharged the system. No leaks could be found. My friend is a lube tech and cycles his AC weekly throughout the Winter. His car is a 2017 and he's on it. I swear I must have a mad German Shepherd Dog gene in my DNA because all I want to do is bite them.