Refrigerant Recovery, Recycling, and Safety Practices
Legal and safe service
Refrigerant service is regulated. Recover refrigerant before opening the system - venting to atmosphere is prohibited for R-134a and R-1234yf. Use certified recovery/recycling equipment, identify the refrigerant, and never mix refrigerants. R-1234yf is mildly flammable, so follow manufacturer procedures and avoid ignition sources. Wear eye protection and gloves; liquid refrigerant causes frostbite, and refrigerant vapor displaces oxygen in low areas.
Understand recovery, recycling, and evacuation as separate steps: recovery removes refrigerant, recycling cleans it for reuse, and evacuation removes air and moisture before charging. Use a micron gauge for vacuum; a system that will not hold vacuum has a leak or moisture. Never open a system without recovering, and cap lines to keep moisture out.
Traps
Questions test that mixing refrigerants is prohibited and that recovered refrigerant of unknown identity must be handled as contaminated. Another trap: confusing recycling with evacuation. Also remember that a leaking system must be repaired, not just topped off, and that refrigerant cylinders must not be overfilled or heated with an open flame.
Worked example
A system must be opened to replace the condenser. Recover refrigerant into the correct cylinder, cap the open lines, replace the part, evacuate to a deep vacuum and hold it, then charge by weight to the underhood label. Skipping the vacuum hold risks moisture and a repeat comeback.