Refrigerant Leak SealantA/C EasySeal is designed to prevent and permanently seal troublesome leaks in air conditioning and refrigeration systems, says Nu-Calgon. A/C EasySeal travels with the system’s refrigerant and reacts with the atmosphere outside the leak to form a permanent seal, eliminating an expensive leak search and repair. Easily installed with a reusable piercing valve and hose, it works with all refrigerants (except ammonia).