Mercedes-Benz has guaranteed compliance with the European Union’s (EU) MAC Directive, to take effect from 2017, by committing to using CO2 in its mobile air conditioning units (MAC).
The company has confirmed it will use R744, a sustainable solution for MAC, in its S- and E-Class models, prior to it becoming standard in other models, including its A, B, and C-Class.
The decision ends a stand off between Mercedes and the EU, who threatened legal action against Germany in September, after it stood by companies like Mercedes (division of manufacturer Daimler) and BMW, who were among the OEMs to criticise proposed alternative HFO1234yf due to its potential to combust in an accident. According to Mercedes, internal tests validated their concerns in heavy frontal impacts.
Previously, the German government, a vocal supporter of CO2 in MAC applications, had approved some Daimler models to continue using R134a, contrary to the EU directive.
Under the EU’s MAC Directive, f-gases with a GWP of more than 150 times greater than CO2 (GWP 1) - namely the widely used hydrofluorocarbon R134a (GWP 1300) – will be prohibited in new cars and vans by 1 January 2017.
In 2012, Mercedes was the first major automotive company to make future commitments to using CO2 in its MAC, along with VW, who were the first to announce in which models it would utilise R744. Compared to HFO1234yf, CO2’s properties make it non-flammable and more efficient, according to Mercedes.
While Mercedes continues the development of its electrically operated compressor specifically for CO2, its other models will continue to use controversial HFO1234yf for the time being.
In 2015, Mercedes, along with other German automobile manufacturers, helped draft the first ever standards for CO2 MAC with the German Association of the Automotive Industry (VDA). The publicly accessible DIN specifications covering R744 components for MAC systems are designed to reduce the cost compared to HFC and HFO-based systems.
That Mercedes is now taking another step and pushing the standardisation of CO2 MAC units will enable other companies to fast-track their development with an advantage, specifically, knowledge of the redesigned hoses, seals and related components required for a system operating at pressures over 100 bar.