Today mobile air-conditioning systems in passenger cars contain a refrigerant paying a major contribution to increasing the greenhouse effect. For the time being, about 30% of the worldwide emissions of hydrofluorocarbons arise from mobile air-conditioning systems in passenger cars [UNEP 2009]. That is why in Europe this refrigerant – according to Directive 2006/40/EC – has to be substituted by a substance less harmful to the climate beginning in 2011.