MAC in the US: HFO-1234yf approved; HFC-134a being phased out ?

On February 28, 2011, the US Environmental Protection Agency (EPA) issued final approval for use of HFO-1234yf in motor vehicle air conditioning in new cars and light trucks. HFO-1234yf had already been approved for use in Japan and Europe. HFO-1234yf, developed by DuPont and Honeywell as a substitute for HFC-134a in mobile air-conditioning (MAC) applications, has a GWP of 4 and has been classified 2L (lower flammability, low burning velocity) in recently published ASHRAE standards.
In addition, EPA has agreed to grant a petition filed by NGOs to withdraw the agency’s approval of HFC-134a (GWP = 1430) for air-conditioning systems installed in new cars. According to the Institute for Governance & Sustainable Development, one of the petitioners, this will be followed by formal “notice and comment” rulemaking to set the phase-out schedule.