Got an older 2.5 ton Trane HVAC, R-22. Where I work, I constantly hear about the problems with 401a systems and not just ready to change it out. About 4 years ago, it developed a leak on one of the condenser tubes. HVAC guy found it, welded it, pressure tested it, and the recharged with R-22...boy that was expensive. Fast forward to now. Still working fine but I can tell by the sound the expansion valve makes and how long it takes for that sound to go away, it probably needs a shot of R-22. My question....should I pay the bucks, I know R-22 is stupid expensive now, and have it "topped" off or if it ain't broke, don't fix it. Thinking too that if I had more Freon, will that increase the pumping pressure and maybe contribute to another leak?