What is the coldest ac refrigerant for automotive?

The coldest refrigerant used in modern air conditioning systems is a synthetic hydrofluorocarbon (HFC) called R-134a. It has an extremely low boiling point of -26.1 degrees Celsius (-14.98 degrees Fahrenheit) at atmospheric pressure, making it very effective at absorbing and removing heat from the air in a car. R-134a is widely used in automotive air conditioners today due to its high cooling capacity and relatively low environmental impact compared to older refrigerants like CFCs and HCFCs. However, due to its high global warming potential, R-134a is being phased out and replaced with more climate-friendly refrigerants such as HFO-1234yf and R-744 (carbon dioxide).