any experience with frozen or stubborn quick disconnect fitting on AC line?

Answer 1

the spring lock quick disconnect are subject to corrosion soaking them down with p.b. blaster and letting sit overnight then following with wd-40 helps don't forget to blow out loosened debris with compressed air before attempting to unlock and separate pipes. note in thankfully rare instances warming the female side of union with a hand held butane torch has worked[ the r-12 or r-134a must be completely evacuated before warming] and pay attention to anything in close proximity and keep a A.B.C. fire extinguisher handy. good luck