Refrigerant! Very interesting. See, you can check the refrigerant in your vehicle system in following ways:
Model Year: If your car is old than 1992 model, then it’s dangerous. The Purest refrigerant form is R-134a which was introduced in 1992. So, the car manufactured before 1992 doesn’t have the purest refrigerant in it and thus the refrigerant present in there is illegal. By the end of 1993, all cars were by default equipped with R-134a. Although R-12 refrigerant were equipped with R-12, but there is a chance that these refrigerants would have mixed and contaminated if you refilled refrigerant in your car after 1993.
Decal: Service information decal in cars helps in detecting the type of refrigerant n your car. Not only that, but also the capacity and level of refrigerant and lubricant can be known by decal.
Service fittings: R-12and R-134a comes with different types of service fittings. What is it if you ask? If helps in reducing the contamination in the refrigerant. R-12 comes with 7/16 inches of service fitting which you can find it on the lower pressure side and 3/8 inches on the higher side. For R-134a, 13mm on the lower side and 16mm on the high pressure side is present. But if you find service fittings which is other than this, it mean the refrigerant in your car is illegal.
And please, my personal advice. Don’t ignore refrigerants in your car especially when you know that it’s illegal. Illegal refrigerants not only damage the AC in the car but it can damage the complete engine. So try to ignore that by maintaining pure refrigerant in your car. Catching fire because of presence of flammable refrigerant is a true story actually, so don’t try to put illegal/ flammable in your car just for fun.