Need To Switch From R12 To R134a?
Auto A/C systems require refrigerants to cool down the cabin. Cars that were manufactured before 1993 utilize R12, which is also known as Freon®. Vehicles that were made after the period use R134a. You should keep in mind that R12 is no longer available because of environmental concerns. Certain theories state the release of R12 has harmed the ozone layer, causing a permanent sunburn on the entire planet. However, certified technicians and auto mechanics still have access to it. They continue to reuse, clean, and recycle the remaining supply of R12. Contrary to popular belief, you can switch from R12 to R134a.
When Do You Need to Switch from R12 to R134a?
If the R12 system is cooling properly and contains a normal charge of refrigerant, you can consider sticking to it. If the system leaks, the recommended solution is to repair it and recharge it with R12. Adding R134a to a R12 system may reduce cooling performance. In addition, the system may require additional modifications depending on the model year of the vehicle.
Switching from R12 to R134a makes the most economic sense when your A/C system needs major repairs such as a new A/C evaporator, A/C condenser, or A/C compressor. The cost of switching refrigerants normally do not add much to the total repair bill. It is fairly easy to convert vintage cars from the 1990s to R134a. For example, you only need to change the compressor lubricant of a vehicle that features R134a-compatible seals, compressors, and barrier-style hoses.
Calculating How Much R134a You Need
R134a is lighter than R12. To get the proper charge during a retrofitting procedure, you must convert the charge weight. Start by finding the refrigerant capacity of your current system. Next, multiply the R12 charge specification by 0.9, i.e. 90 percent. Finally, subtract 0.25 pounds from that amount. For example, if you have 3 pounds of R12, you need 2.45 pounds of R134a. Or you need 1.28 pounds of R134a for the 1.70 pounds of R12 your car currently has.
In many cases, you will need to fill the system with approximately 75 percent to 85 percent of the factory specified capacity. When it comes to overcharging and undercharging, R134a has a lower tolerance. If you add too much R134a refrigerant, you will decrease A/C performance.
How to Switch to R134a
Today, the federal law requires the permanent installation of R-134a fittings on both low and high service ports. The law was implemented to reduce the chance of refrigerant cross-contamination during auto servicing. If you need to switch from R12 to R134a, you will do fine by following vehicle manufacturer recommended retrofit procedures. The main steps include:
- Old mineral oil removal
- Receiver/dryer and accumulator replacement (replacement unit must contain X-7 desiccant)
- Replacing O-rings
- Replace or install a high-pressure cutout switch
- Change the expansion valve or orifice tube
- Adding PAG oil
- Recharge A/C system with R134a
- Installing a new A/C condenser (for improved cooling performance)
There is a way to enhance cooling performance when switching from R12 to R134a. You can consider installing a variable valve orifice tube in place of a standard one. They offer better cooling capabilities at low or idle speeds.