Refrigerants

What is the difference between R-134a and R-1234yf?

R-1234yf is the newer refrigerant with a much lower global warming potential; it is mildly flammable and needs its own service equipment, fittings and procedures.

Why should I use a refrigerant identifier before recovering?

Short answer: An identifier confirms the refrigerant type and purity, so you do not contaminate your recovery machine and supply with mixed or sealant-filled refrigerant.

Vehicles come in with mystery refrigerant more often than you might expect. Someone may have topped off with the wrong product, used a blend, or added a hydrocarbon refrigerant. Recovering that into your machine contaminates its tank and every vehicle you charge afterward.

A refrigerant identifier samples the system and reports the type and purity. If the refrigerant is contaminated, you can recover it into a separate container designated for contaminated refrigerant and handle disposal properly, protecting your main equipment.

Some identifiers also detect air and certain contaminants. Sealants are another risk; a sealant detection test can protect your machine, since sealant can clog hoses and valves. Wear eye protection and gloves when connecting to any refrigerant system.

Can I convert an R-1234yf vehicle to R-134a?

Short answer: No; retrofitting a vehicle designed for R-1234yf to R-134a is not an acceptable practice under EPA rules, and the system and fittings are designed for the original refrigerant.

Some owners ask about switching an R-1234yf system to R-134a because R-134a is familiar. It is not a legitimate repair. EPA's rules for new light-duty vehicles do not accept R-134a in place of the refrigerant the vehicle was built for, and the vehicle maker designed the system, oil, fittings and controls around R-1234yf.

Adapters that let an R-134a hose connect to an R-1234yf port defeat the protection the different fittings provide and can contaminate the system and service equipment. A contaminated system may need its refrigerant sent off for reclamation, which costs more than doing it right.

The right path is to service the system with R-1234yf equipment and the specified oil, or refer the job to a shop that has it. Remember that R-1234yf is mildly flammable, so keep ignition sources away and use equipment designed for it.

Why should A/C refrigerant be charged by weight instead of by gauge pressure?

Short answer: Modern systems hold small, precise charges, and pressure changes with temperature and load, so weighing in the exact specified amount is the only reliable way to get the charge right.

Each vehicle has a specified refrigerant charge listed on an under-hood label and in service information. Many current systems hold small charges, so being off by a few ounces can noticeably change performance. Overcharging raises pressures and can damage the compressor; undercharging reduces cooling and oil return.

Gauge pressures depend on ambient temperature, humidity, engine speed and airflow across the condenser, so charging to a pressure leaves too much guesswork. Instead, recover what is in the system, evacuate properly, then charge the specified amount by weight with a refrigerant scale or a service machine that weighs.

After charging, use gauge readings and vent temperatures as a performance check rather than as the charging target. Keep the refrigerant tank upright or as the scale maker directs. Wear safety glasses and gloves, and never heat a refrigerant tank with a torch.

What should I do if I find A/C stop-leak sealant in a system?

Short answer: Do not connect your recovery machine until you know; sealant can clog machines and components, so use a sealant check and follow your equipment maker's guidance for contaminated systems.

Sealant products sold for do-it-yourself recharging can harden when exposed to moisture or air. Inside your recovery machine they can clog filters, valves and hoses, which can mean expensive repairs. In the vehicle they can restrict the expansion device or receiver drier.

Ask the customer whether a recharge kit was used, and look for evidence such as a recharge can fitting left on a port. Some shops use a sealant detection kit before connecting their main machine. If sealant is present, use a dedicated recovery setup for contaminated systems and send the refrigerant for reclamation as required.

Replace affected components as the vehicle maker directs and flush where permitted. Tell the customer why the repair costs more. Wear safety glasses and gloves, since contaminated refrigerant and oil can spray when hoses are disconnected.