Eberspaecher has introduced two roof-mounted air-conditioning systems using propane (R290) for buses. The AC135 and AC138 EVO models are available for both factory installation and retrofitting in diesel vehicles, offering a climate-friendly solution in response to tightening EU refrigerant regulations.
In light of the EU F-Gas Regulation and ongoing plans to ban PFAS substances, the use of natural refrigerants is becoming increasingly important. Eberspaecher’s AC135 and AC138 EVO systems utilize propane, which has a low global warming potential (GWP ~3) and operates effectively in ambient temperatures ranging from -15 to +55 °C. For cooler climates, the company also offers CO₂ (R744)-based heat management systems.
The systems use a direct AC setup, allowing refrigerant to circulate without an additional heat exchanger. This design reduces weight, energy loss, and the number of components required. According to Eberspaecher, the propane version of the AC135 maintains identical interfaces, dimensions, and controls as its synthetic counterpart, facilitating integration into hybrid and battery-electric buses. Safety measures for propane use are based on sealing and ventilation concepts from the rail industry.
Eberspaecher has also introduced a retrofit solution for diesel buses. Since propane and CO₂ are not compatible with conventional mechanically driven compressors, the company has developed a system using a generator to power an electric compressor. This enables, for the first time, the retrofitting of diesel buses with air-conditioning systems that use natural refrigerants.
Both the AC135 and AC138 EVO models feature the E-Control module, which integrates all thermal management functions and connects with vehicle systems via CAN interface. Operators can access diagnostics and fleet data through the e-connected platform, which supports real-time monitoring and over-the-air updates.
