The present invention relates to a system for controlling the temperature of a fluid additive for an exhaust system of an internal combustion engine. The system has means for exchanging heat between the additive and a refrigerant circuit of a refrigerant system. The fluid additive is preferably a NOx-reducing additive, in particular a urea-water solution, for an SCR catalytic converter system of a motor vehicle. Here, a direct or indirect exchange of heat may be provided between the refrigerant circuit of the refrigerant system, specifically in particular of a vehicle air conditioning system, and the additive.