The EU MAC directive restricts refrigerant use to those with a global warming potential (GWP) of less than 150, thereby banning HFC-134a, which was globally used until now. Therefore, nearly all Tier 1 multi-national MAC suppliers have already developed systems with low-GWP refrigerants. The dominant options here are unsaturated-HFCs (u-HFCs) and CO2. European manufactures will be forced to implement low-GWP refrigerant systems on the market by 2017. As a result, car manufacturers initially agreed to use the purpose developed u-HFC-1234yf. After tests by Daimler showed that u-HFC-1234yf ignited during crash testing, other German manufacturers, including the VW group and BMW joined Daimler’s announcement to opt for CO2.
In the US, only refrigerants approved by the EPA’s SNAP Program may be used. In the low-GWP category for mobile air conditioning HFC-152a, CO2, and u-HFC-1234yf, are SNAP-approved. California’s proposed Low Emissions Vehicle regulation (LEV III) requires cars to use refrigerants with a GWP of 150 or lower. Also, the US CAFE (Corporate Average Fuel Economy) standards set minimum efficiency standards for cars, which recently include a credit system that gives points if a car has an efficient MAC system or uses a low-GWP refrigerant.
Because of the homogeneous global MAC market, there is a tendency for car manufacturers to opt for MAC units fulfilling the most stringent environmental and safety restrictions in the world, which come from the EU and the US.