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R-1234yf is sold in 10-lb containers because of price, vs. the 30-lb containers used for R-134a. R-1234yf containers all have red bands to denote the mild flammability. 

EPA's 2021 A/C refrigerant rules accelerate R-1234yf changeover

The industry transition to a low global-warming-potential (GWP) air conditioning refrigerant, already underway in Europe, moves into high gear in the U.S., as CAFE (Corporate Average Fuel Economy) regulations add incentives. Car manufacturers receive substantial CO2 credits that translate to more miles per gallon, and a new EPA phaseout schedule for R-134a has been adopted.

Per new EPA regulation, the long-used R-134a cannot be installed in new cars and light trucks built for domestic sale after 2021MY. Although this rule is limited to those vehicles, similar regulations for medium/heavy-duty trucks are coming this year, so the 2021 deadline may affect all domestic vehicles by that time. Some vehicles for export will still be able to use R-134a systems until 2025MY.

In the meantime, Daimler, which had charged that the alternative refrigerant R-1234yf posed potential fire safety dangers, has finally agreed to use R-1234yf systems in its Mercedes vehicles for markets where the refrigerant either is mandated or is effectively pressed for by regulatory bodies (as in the U.S.). However, no rollout schedule has been announced. Daimler will add an underhood "fire extinguisher"—an argon gas canister with spray lines directed at all parts that its engineers say might become hot enough for a leaking refrigerant to ignite.

Because low GWP R-1234yf cannot be retrofitted to R-134a systems, production of R-134a will continue indefinitely for service. The R-1234yf CAFE credits are 13.8 g/mi for cars, 17.2 g/mi for trucks. (GWP, a metric used by environmental regulatory agencies worldwide, is a measure of how much a given mass of a gas contributes to global warming. It is a relative scale which compares the amount of heat trapped by greenhouse gas to the amount of heat trapped in an equal mass of CO2. The GWP of CO2 is by definition 1.)

The value of storing CAFE credits for a low GWP refrigerant enticed Fiat Chrysler Automobiles (FCA) into beginning its changeover in 2014MY. General Motors has had just one entry in that period, the Cadillac XTS, but GM will be virtually across the board by the end of this year. Ford reportedly will begin its changeover in April with the Escape, but no details of its rollout are available. Sending vehicles with either refrigerant down the same assembly line is not a difficult process.

Warranty payments

The "street retail" price of R-1234yf—over $100 lb/ $220 kg has reportedly dropped slightly for volume buyers, and there are internet advertisements (of unknown validity) for as low as $72.50 lb ($160 kg). However, that's still much higher than the typical $3 lb/$6.60 kg for R-134a.

FCA's list price for R-1234yf is per ounce—because its dealers are instructed to bill the factory only for the additional amount (total refrigerant charge at the conclusion of the repair, less amount recovered from the vehicle system at the start). The recovery/recycle/recharge machines have a charge accuracy of ±1 oz and print out the amount added; the printout must be attached to a warranty claim.

Total refrigerant charges have been coming down in recent years, and those for FCA's R-1234yf systems are as low as 13 oz (370 g) on the Alfa Romeo 4C to a high of 25 oz (709 g) for the Chrysler 300 and Dodge Charger, with most in the 16-18-oz range (454-510 g).

FCA's launch of the low GWP refrigerant has gone very smoothly. At the recent Mobile A/C Society (MACS) convention attended by Automotive Engineering, Alan McAvoy, technical advisor at the FCA Midwest Business Center, told the audience: "We currently have R-1234yf vehicles that have been on the road for over three years and have built over two million total. Service to this point is primarily limited to collision damage, plus a few with minor hose or fitting leakage."

Although R-134a will perform comparably to R-1234yf, EPA's Rebecca von dem Hagen, of the agency's Stratospheric Protection Division, told the MACS convention that a shop changing an R-1234yf system to R-134a would constitute the offense of tampering with an emissions control. Each refrigerant requires specific service valve fittings to discourage any attempt, both on the vehicle and the refrigerant containers.

R-744 work continues 

EPA will allow sale of small cans of R-1234yf to the do-it-yourself market, provided the cans have self-closing valves to minimize venting. This is based on California's regulation for R-134a, which includes a $10/can deposit system.

An attempt by Mexichem to develop R-445a as a lower-cost blend refrigerant alternative to R-1234yf, has been put on hold. Work on a series of enabling SAE standards has stopped, too. The blend consists of 85% R-1234ze (an olefin in the same family as R-1234yf), 6% carbon dioxide and 9% R-134a, so whether it faced the 2021 deadline for R-134a is now moot.

Members of the VDA, the German automakers association, are continuing consortium development of R-744 (CO2) refrigerant. Daimler engineers hope for its 2017 introduction on some Mercedes E- and S-Class European models. As a result, the SAE program to develop enabling standards for a U.S. introduction has not been reactivated.

Before R-744 cars would be sold in America, EPA would be asked to modify its requirement that no refrigerants can be vented, so must be recycled (or destroyed)—a rule that includes R-1234yf despite its low GWP. CO2 is both natural and inexpensive, and any requirement to recycle it would be environmentally questionable. Emissions would be produced by the effort, perhaps in excess of the low GWP (just 1.0) of the refrigerant itself. EPA recognizes this issue but has not specifically announced it will address an exemption.

In the meantime, there is no market-ready low GWP alternative, hence the changeover to R-1234yf. Even Daimler, which has most strongly questioned its safety and famously showed videos of a laboratory test that demonstrated potential dangers from its mild flammability, has no choice at this time. The Daimler test indications were widely disputed, as others in the industry attested to R-1234yf safety.

The European Union has initiated lawsuits to force compliance by Daimler to EU's low- GWP rule for "new type" vehicles. So the automaker has finally agreed to use R-1234yf systems, but with the on-board argon fire-suppression system noted earlier.

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