We are going to develop a comparison between the refrigerant gases R134a and one of its substitutes in the new automotive air conditioning systems, which is R1234yf.
- R1234yf is a substance remarkably similar in cooling performance to its predecessor, R134a, while having a Global Warming Potential (GWP) of 1 compared to the GWP of R134a, which is 1430.
- Both R134a and R1234yf are pure refrigerants, meaning they are composed of a single gas. Therefore, both R134a and R1234yf can be recharged in both liquid and gas phases without any issues.
- R1234yf requires specific PAG, PVE, and POE oils designed for this gas. It’s important to ensure that the oil used is compatible with R1234yf.
- R1234yf is highly corrosive, so only clean and properly specified lubricants can protect the system.
- R134a uses POE oil in conventional refrigeration and PAG oil in automotive air conditioning.
- R1234yf has low toxicity, is slightly flammable, and shows excellent compatibility with most materials. It is classified as A2L, group L2 in terms of safety. Similarly, R134a is non-toxic, non-flammable, and classified as A1, L1.
- In addition to the automotive sector, both R134a and R1234yf are used in chillers for air conditioning in buildings and machine cooling.
- Vehicles using R1234yf have different service fittings compared to vehicles using R134a to prevent cross-contamination with different refrigerants. For example, adapters are required to connect pressure measurement gauges.
- R1234yf is more expensive than R134a.
- It is not recommended to change from R1234yf to R134a for legal reasons.
- Although the system may operate and cool when switching from R1234yf to R134a, its performance and capacity will be affected, and some inconveniences may arise, which we will discuss next.
- R1234yf systems that control freeze protection by pressure may lose cooling performance if charged with R134a. This is due to the lower adjustment requirement of R134a.
- Mixing R134a with R1234yf will alter the refrigerant pressure and may result in evaporator freezing in pressure-controlled systems, reducing the airflow.
- The expansion valve setting for R1234yf refrigerant is different compared to R134a. Changing from R1234yf to R134a may result in a system with incorrect refrigerant flow and heat exchanger mal-distribution, leading to a loss of cooling performance or durability issues.
- Changing from R1234yf to R134a can result in an increase in suction line pressure drop, reducing the efficiency of the equipment. This can be particularly damaging in the case of dual evaporator systems.
