All car models built before 1995 uses R12 as refrigerant for car AC system. Since then R12 is replaced by R134A because of lower GWP. You cannot use R134A in car AC’s deigned for R12 as R134A operates at a much higher pressure.
You have to retrofit your old car AC system to use r134a using below steps .
- Check the sticker below the hood to verify that your car uses R12.
- Evacuate the last traces of R12 using recovery machine at licensed dealer.
- Replace the old dryer with a new one to prevent any kind of clogging. Also replace the O rings (it will be present inside the dryer).
- Vacuum your AC till both the blue and the red meters show a reading of below zero.
- Read the service manual to find the amount of refrigerant to fully charge your ac. After that go and buy R134 Retrofit kit and Cans. One can is of 12 ounces.
- Also purchase oil charge (ester oil and PGA oil).
- Connect the retrofit kit to your car. Start your car and set AC to maximum. First add the oil charge and after that connect the refrigerant can.
- Check the car air for coldness. If it is cold then you have successfully charged your system.
Important points to keep in mind while retrofitting systems
- Keep your hands away from the moving parts to prevent any kind of burning.
- It is illegal to release r134a in environment.
- Never overfill or under fill your ac system. Both the conditions is damaging to your ac system. It is best to check your service manual and fill as per specifications provided.