The new candidate, HFO-1234yf, is currently being evaluated by automotive manufacturers. Preliminary data suggests that it has the potential to deliver the best balance of properties and performance, versus existing candidates, such as CO2 (R744) and HFC-152a, in MAC systems.  It is energy efficient, exhibits low toxicity in testing to date, and can potentially be used in existing mobile air conditioning systems.  Unique attributes of 1234yf include:

• Lower total greenhouse gas emissions versus current HFC-134a and other candidates, as a result of good energy efficiency, lower GWP (4)   and cooling performance in hot and moderately hot climates;
• Lower operating pressures than CO2 systems, offering greater safety for consumers and service technicians;
• Exceeds the EU low-GWP directive with GWP of 4, with the potential to be used in all cars; and
• Compatibility with existing technology, enabling a cost-effective transition away from HFC-134a, higher reliability and lower warranty costs.

DuPont firmly believes that continued development and evaluation of low GWP products will lead to a superior solution for the replacement of HFC-134a.  An ideal refrigerant offers the best combination of environmental, economic, safety and performance attributes for the global automobile industry. Technical and safety issues regarding the use of CO2 in car air conditioning remain unresolved by the industry, despite years of development.