Mercedes goes eco with CO2 air conditioning. The new system explained

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Mercedes decided to go green and use CO2 air conditioning systems instead of the synthetic Tetrafluoroethane (R123a) refrigerant fueled ones for all its models.

This move brings the German brand in line with EU regulations in the wake of a long legal battle over the legitimacy of the European directive banning the R123a for all vehicles produced after 2013.

The revised CO2 air-conditioning systems will first make an appearance on the next generation E-Class and the current S-Class, from the beginning of 2016. Next, the CO2 fueled climate controls will be implemented across the range in the following years, popping up on the A-Class, B-Class, C-Class and so on.

All the components had to be redesigned to comply with the new refrigerant. This means all-new hoses and seals too. The main reason is the high operating pressure of more than 100 bar at which CO2 air conditioning systems work at, compared to the 10 bar pressure conventional systems.

For the past 25 years, Tetrafluoroethane (R123a) has been the preferred air-conditioning refrigerant for most carmakers, not only Mercedes. Its alarming global warming potential or GWP score going as high as 1300 has spurred the wrath of environmental activists all over the world with Europe being the first continent to officially ban R123a. Current regulations require a maximum GWP of 150. Carbon dioxide’s score is 1 and is non-flammable.

EU regulators have proposed a replacement refrigerant as well, Tetrafluorpropen (R-1234yf). Even if considered as more environmentally friendly, the new substance has been promptly rejected by Mercedes. The German carmaker has quoted internal tests showing flammability issues arising in head-on collision scenarios. VW and BMW confirmed the results joining Mercedes in the anti-R-1234yf camp.

Until the full scale implementation of the new CO2 based air-conditioners, current systems will use the controversial Tetrafluorpropen (R-1234yf). For safety reasons, though, petrol Mercedes models have received a supplementary gas generator. Its goal is to keep the refrigerant cool by releasing inert argon gas at the hottest spots, preventing it from starting a fire.

Diesel-engined Mercedes cars, on the other hand, have not received the same upgrade. Lower operating temperatures mean argon is not necessary for keeping Tetrafluorpropen (R-1234yf) cool in case of an accident. The same refrigerant is also bound to be used by the current hybrids in the E-Class and S-Class line-ups.