Sometimes the cure is worse than the disease. Environmentalists have forced the use of a new air conditioning refrigerant in Europe, saying it is better at cutting down on global warming, but it turns a out that the latest concoction from DuPont or Honeywell can go up in flames during an accident.
As a result, Mercedes-Benz in North America is recalling 2013 SL-Class vehicles manufactured from December 2011 through May 2012 originally equipped with so called R1234yf refrigerant and replacing it with the older R134a gas, along with new refrigerant hoses designed for R134a. The new environmental regulations up to this time appeared headed for global implementation. The new Cadillac XTS is one of the first cars in the U.S. using this new refrigerant as GM is in the process of phasing in R1234yf.
Daimler is now pressing regulators to drop the new refrigerant requirement and allow the continued use of R134a. It has publicly said it now refuses to use the new concoction. Previous tests of the new refrigerant showed it to be safe, but Daimler carried out a series of additional tests as part of a new test scenario developed in-house that goes beyond the legally prescribed requirements.
DuPont, standing to gain considerable revenue from its patented, R1234yf gas, issued a statement: “Based on extensive data, and on independent risk assessments, HFO-1234yf can be used safely as an automotive refrigerant.” DuPont claimed that it was “surprised” by the statement released by Daimler. “According to the release, the test they conducted did not involve other industry members or undergo peer review,” said DuPont.
Honeywell noted that previous evaluation tests were conducted within the Cooperative Research Program led by SAE, the independent global association of automotive engineers, together with leading automakers, including Daimler and several independent institutes worldwide.
Daimler said that all the data would be released to other automakers and regulatory bodies, and that the test was reproducible.
In the Daimler test, the refrigerant is released at high pressure near to hot components of the test vehicle’s exhaust system. This Daimler claims corresponds to a serious head-on collision in which the refrigerant line is severed. Daimler also says that the results demonstrate that refrigerant which is otherwise difficult to ignite under laboratory conditions can prove to be flammable in a hot engine compartment. Similar tests of the current R134a refrigerant did not result in ignition.
According to the Mobile Air Conditioning Society – a respected industry trade group – DuPont co-developed HFO-1234yf in response to Europe’s Mobile Air Conditioning Directive, which requires an automotive refrigerant with a global warming potential (GWP) under 150. HFO-1234yf refrigerant has a GWP of 4, which is 99.7% lower than the R134a refrigerant used in most cars today, which was developed as a replacement to R12. R135a has a GWP of about half that of R12.
