Eberspächer, a German manufacturer of thermal management systems, has announced plans to introduce propane (R290) versions of its AC138 EVO and AC135 solutions for buses and coaches.
The R290 products are slated to launch in 2026 and will be officially unveiled at the Busworld 2025 exhibition in Brussels, October 4–9.
The new systems are designed to meet increasing market demand for high efficiency technologies that use future-proof refrigerants, according to the manufacturer.
“Eberspächer is continually developing its portfolio of air-conditioning systems for all drive types and the use of natural refrigerants,” the company said.
The AC138 EVO, currently only available with CO2 (R744), provides air-conditioning for the passenger compartments of electric city buses and entered into series production earlier this year. “Several units” have been delivered and are being integrated into fleets, Eberspächer told NaturalRefrigerants.com.
While the existing system includes a simplified air circuit and an energy recovery function to maximize efficiency, the company noted that R744’s performance drops in high ambient temperatures. The new R290 version is designed to maintain efficiency under such conditions.
The AC135 system, launched in 2023, is designed for buses with both electric and conventional powertrains and supports cooling capacities of 25–50kW (7.1–14.2TR). Until now, the unit has relied on synthetic refrigerants, but increasing regulatory pressure is pushing manufacturers toward low-GWP alternatives like propane.
“Synthetic refrigerants are threatened with the possibility of becoming obsolete in Europe in the medium term due to the gradual reduction in available quantities worldwide and further restrictions on the use of PFAS [per- and polyfluoroalkyl substances], primarily by the EU,” it explained.
Once available, the propane-based AC135 will serve range of vehicles, including electric minibuses, intercity buses and coaches. The unit will also be the first natural refrigerant-based thermal management system of diesel-powered buses, according to the manufacturer. Depending on the configuration, the system will offer cooling capacities of 25–50kW.
“Eberspächer is continually developing its portfolio of air-conditioning systems for all drive types and the use of natural refrigerants.”
Eberspächer
Alongside the AC138 EVO and AC135 systems, Eberspächer will also showcase its Hydro Control System (HCS) and cloud-based E-Control module at its Busworld 2025 booth, number 316 in hall 3. Both solutions are designed to enhance the efficiency and control of thermal management processes in buses.
Natural refrigerants in MAC
A growing number of mobile air-conditioning (MAC) applications are turning to propane and CO₂ as the world phases down the use of high-GWP refrigerants like R134a, a commonly used refrigerant in MAC systems with a 100-year GWP of 1,530.
Historically, the majority of natural refrigerant-based thermal management systems in passenger vehicles – including cars and buses – have used CO2. However, in recent years, several manufacturers have begun exploring the potential of propane. For example, ZF has a market-ready R290 system for electric vehicles, pending regulatory approval, while Munich’s suburban rail system placed an order for 1,350 propane-based HVAC units in late 2024.
The topic of natural refrigerants in MAC will be explored in depth at the ATMO MAC Summit 2025 × TU Berlin, which will be held in Berlin September 23–24. The event is organized by ATMOsphere, publisher of NaturalRefrigerants.com.
