R-134a is a hydrofluorocarbon (HFC) that has been used as a refrigerant in automotive air conditioning systems since the early 1990s. It is a colorless, non-flammable gas that is safe to use in confined spaces. R-134a has a boiling point of -26.5 degrees Celsius (-15.7 degrees Fahrenheit) and a freezing point of -101 degrees Celsius (-149.8 degrees Fahrenheit).