1. The most obvious way is to look for the R-134a sticker. This sticker is usually found in the engine bay, and it will indicate that the car has been converted to use R-134a.
2. You can also look at the air conditioning system itself. If the system has been converted to R-134a, the compressor will have a different type of fitting than a car that still uses R-12. R-134a compressors have a flare fitting, while R-12 compressors have a barb fitting.
3. You can also check the Schrader valves on the air conditioning system. If the car has been converted to R-134a, the Schrader valves will be larger than the Schrader valves on a car that still uses R-12.
4. If you are not sure whether or not your car has been converted to R-134a, you can take it to a mechanic or automotive shop and have them check the system for you.
