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Daimler will phase in CO2 from next year. Picture Special

Daimler has agreed to use the refrigerant R1234yf in its air-conditioning systems, after almost three years of resisting the EU Mobile Air Conditioning Directive.

But at the same time it announced that it will start phasing in its first CO2 air conditioning in Mercedes Benz models as soon as 2016, and called on other carmakers to follow suit.

Daimler said it will install “specific protective devices” to protect its vehicles that will use R1234yf in the event of a head-on collision, using an argon gas suppressant to avoid the refrigerant mixing with hot engine components.

The German carmaker has become the scourge of R1234yf producers and European regulatory authorities alike for continuing to install R134a in its new vehicles, in breach of the MAC Directive, which required use of refrigerants with a GWP under 150 in new models from 1 January 2013.

Daimler’s argument, that its own head-on collision testing found a fire risk with R1234yf, has been widely discredited – with the carmaking industry research body SAE International and the European Commission’s research arm the Joint Research Centre all concluding that R1234yf was safe to use in cars and that Daimler’s risk scenarios were unfounded. SAE went as far as to say that Daimler’s collision test was “not an appropriate test to verify the safety of refrigerant applications in vehicles”.

Daimler has been waging a lone battle against the Directive, with other carmakers adopting the HFO, which is currently the only approved refrigerant for automotive use under 150 GWP. However, an R1234ze/CO2 blend from Mexichem – R445A – is currently undergoing advanced testing with SAE’s working groups.

Honeywell, the manufacturer of R1234yf, released a statement in response to the news, giving no clue as to the frustration of three years of argument. It said: “HFO-1234yf-based systems are more energy efficient, offer better environmental performance, and are safer and more cost-effective than CO2-based systems. Honeywell has always maintained that HFO-1234yf can be used safely with relatively minor changes to engine compartment design. Given this, it is not surprising that Daimler, like other major automakers, has now found a way to incorporate HFO-1234yf through a solution tailored to their specific car design.”

The European Commission is understood to still be in the midst of infringement proceedings against Germany for non-compliance with the Directive.

But Daimler said last month that its move was designed to comply with the 2017 phase of the MAC Directive, which requires the low-GWP refrigerant to be fitted in all new vehicles, rather than just new models.

In a statement, it said: “In order to comply with the legal provisions going into effect in 2017, Mercedes-Benz will equip its vehicles with air conditioning systems that meet all the relevant performance and safety requirements.

The Stuttgart-based automobile manufacturer will exceed the EU’s climate protection requirements. From 2017, it will offer in Europe the S- and E-Class as the first production passenger cars equipped with CO2 air conditioning systems.”

The carmaker said the CO2 offered comfort advantages, describing it as a “premium solution”: “Thanks to their especially quickly available and high cooling performance, CO2 air conditioning systems swiftly provide for a pleasant feelgood climate inside vehicles even in very hot weather.”

Daimler’s new AC systems

Daimler said that the use of CO2 required extensive component redesign to accommodate a pressure of more than 100 bar – ten times higher than conventional AC systems. It said that it had has drafted corresponding standards together with other carmakers and suppliers in the VDA trade body and that the DIN specification would “offer other companies an opportunity to quickly launch development activities of their own.

This would create the prerequisites for swift market penetration by this high-tech air conditioning system”.

The manufacturer went on to say: “Mercedes-Benz has assumed a pioneering role in this respect. It is the first automobile manufacturer to award not only development contracts but also to place production orders for CO2 air conditioning systems and their components.

The firm said that deployment throughout the entire vehicle fleet will not be feasible by the MAC Directive all-model deadline of 1 January 2017, so it would install R1234yf, as the only available option.

It said: “In order to ensure a continued high standard of safety for its customers in the future, Mercedes-Benz has carried out extensive testing on all its vehicle models. The result is a comprehensive package of vehicle’s specific measures in order to guarantee Mercedes-Benz’s high safety standards for the models using the R1234yf refrigerant.”

The specific device is a patent-pending system which, in the event of “a severe frontal collision”, will release an inert argon gas specifically at the relevant hot spots to prevent the refrigerant/air mixture from reaching the hot engine components.

Even with this statement, the carmarker added a final shot across the bows of its critics, summarising that its proprietary system “effectively keeps the mixture from bursting into flames”.

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