 This week in the shop, we're working on a 2014 GMC 2500 HD, and it came in with a repeat air conditioning system failure. It had been charged up a couple other times at some other places, and it just continued to lose its refrigerant. Well, we did the whole sniff test and went over the whole vehicle and looked for visual leaks, and sure enough, we found a tiny crack in the AC condenser, which is actually pretty common on these 2014s.