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Performance and climate impact assessment of R152a and R1234yf as drop-in replacements for R134a in automotive AC systems

As the phase-out of R134a accelerates due to its high global warming potential, identifying efficient and climate-friendly alternatives becomes critical. This study puts R152a and R1234yf to the test under realistic operating conditions to evaluate their technical viability and environmental trade-offs. 

Researchers from National Ilan University in Taiwan conducted a comparative analysis [1] of R152a and R1234yf as direct (drop-in) replacements for R134a in mobile air conditioning (MAC) systems. The experiment was carried out using a test bench that simulates real-world vehicle operating conditions, including variable ambient temperatures and engine loads, to reflect actual driving scenarios. 

 

Each refrigerant was tested at its optimal charge level: 

  • R152a at 75% of the original R134a charge 
  • R1234yf at 110% 

Measurements included cooling capacity, compressor power consumption, energy efficiency ratio (EER), and total equivalent warming impact (TEWI), integrating both direct emissions and indirect energy-related emissions. 

 

Key findings 
  • R152a outperformed R134a with 11.26% higher energy efficiency and superior cooling performance, while also reducing compressor power. 
  • R1234yf had comparable efficiency to R134a but delivered lower cooling capacity. 
  • TEWI analysis revealed that although R1234yf has a lower GWP, R152a becomes the more climate-beneficial option for vehicles driven more than 4.9 hours per day, thanks to its higher thermal efficiency. 
  • Safety note: R152a is mildly flammable (A2), requiring risk mitigation in system design. 

 

Conclusion 

Both refrigerants are promising low-GWP substitutes for R134a, but R152a offers superior performance and lower total climate impact in high-use scenarios, making it a strong candidate for future MAC applications—provided its flammability risks are managed appropriately. 

 

 

Did you know? The IIR has established a dedicated working group on “Electric Vehicle Thermal Management Systems”, which focuses on advancing research and promoting innovation in the thermal management of electric vehicles. More information about the group's objectives and activities can be found here. 

 

 

Source 

[1] Yi-Jia Wei, Tun-Ping Teng. Evaluating retrofitting and operational efficiency of automobile air conditioners using environmentally-friendly refrigerants. Applied Thermal Engineering, Volume 268, 1 June 2025, Article 125874. https://doi.org/10.1016/j.applthermaleng.2025.125874