Do leak sealers actually work?

Commercial chemical refrigerant leak sealers—marketed as aerosol or liquid additives designed to circulate inside closed air conditioning loops—can successfully seal tiny, microscopic pinhole leaks in metal copper tubing or rubber O-rings, but they are not a guaranteed fix for major structural cracks or loose flare connections. These sealants react chemically with moisture and air at the exact point of an escaping pressure drop, forming a hardened plug over the breach. However, many professional HVAC technicians advise caution because chemical sealants can inadvertently clog delicate electronic expansion valves, service ports, and expensive recovery machinery. You can troubleshoot by assessing leak size with gauge tests. You can verify proper repair when professional brazing or mechanical flare tightening permanently restores system integrity without risking component clogs.