Updated at: 14-08-2022 - By: Lucas

In 2021, the R12 refrigerant will be fully phased out, leaving older automobiles with no refrigerant for their AC systems. Is R134A the best replacement refrigerant for R12?

Even if you’ve already bled out the R12 and replaced it with R 134a, the system must be re-adjusted to use R 134a or it may leak, corrode copper, and not provide the necessary lubrication for optimal functioning.

Let’s take a moment to explain what these codes signify and why R12 has been phased out of use before we get into the various ways of changing your air conditioning system to accept R134A.

The R12 and The R134A Refrigerants Explained

What Happens If You Put R134A In A R12 System

Refrigerator refrigerant R12 has been in widespread usage since the 1950s, when it was first introduced. However, R12 remained the predominant refrigerant used in automobile air conditioning systems.

Chlorine, an ozone-depleting chemical, was detected in R12, making it unsuitable for continued use by the Environmental Protection Agency. Vehicles have been using R134A since 1996, although the R12 is still available for those who are caught in the middle of the transition. However, production and distribution of R12 will cease in 2021, making it increasingly difficult and expensive to acquire.

What Happens If You Mix R12 and R134A?

The HFC (hydrofluorocarbon) base of R134A is a green solution that has no impact on the ozone layer or greenhouse impacts. Using R134A as a direct substitute for R12 is not recommended because of its different chemical composition. In fact, it is a crime to combine the two.

Even if there isn’t a tremendous explosion as some claim, mixing the two is still not a smart idea. As a result of a heat-induced chemical reaction, a black coating will form inside the entire air conditioning system due to the two distinct chemical components.

Can You Add R134A Into An R12 System?

There’s no guarantee that R134A can be used as a replacement for R12 even after it’s been flushed out by a professional to prevent the emission of poisonous gas into the atmosphere. As a result, the air conditioning system will be affected by the chemical difference between the two. A non-upgraded system that uses R134A will experience refrigerant leakage since it needs different lubricating oils, corrodes copper, and is generally corrosive.

How To Add R134A Into An R12 System

What Happens If You Put R134A In A R12 System-2

If you want to use R134A in an R13 air conditioning system, you’ll need a specialist to remove the rest of the R12. Installing the new coolant and retrofitting the system is straightforward, but there are dangers associated with doing so. Changing the receiver dryer while you’re at it is a better option than having to bleed the system afterwards, as it’s not expensive.

Equipment You’ll Need:

As of the date/time specified, prices and availability are subject to change. A customer who purchases this item will be subject to the price and availability information that is displayed at the time of purchase on [the relevant Amazon site(s), as applicable].

However, you’ll need to verify your vehicle’s official retrofitting handbook for the specific parts and amount of PAG oil that are required for your vehicle’s system. After that, you’ll be able to find the necessary parts much more quickly by using the links provided above.

Steps To Retrofit The R12 To A R134A System:

  • Locate the receiver dryer and check if all of the R12 has been bled out. 
  • Remove the low-side fitting that’s located on a pipe below the dryer and swap it with the conversion part.
  • Mount the conversion fittings on the new receiver dryer.
  • Remove the old receiver dryer and O-rings.
  • Put some PAG oil on the thread of the new dryer, and install it along with new O-rings.
  • Follow the instruction manual for the vacuum pump, and draw the air out of the system.
  • Close the pump valves and wait a while to see whether the gauges rise, which would indicate the system isn’t properly sealed.
  • Add the R-134a refrigerant into the system.
  • Use the PAG oil injector to add the oil to the system per the manufacturer’s instructions

I strongly recommend viewing the accompanying video lesson for the final two phases and a more in-depth look at how to retrofit the air conditioning system. In terms of air conditioning systems, I’m not an expert by any means, and I won’t mislead you by pretending to be one. I prefer to have my cars serviced by a professional because it’s simple to overcharge the AC and ruin the pricey AC compressor.


What Happens If You Put R134A In A R12 System-3

What is R12 refrigerant used for?

R12 was the primary refrigerant for home appliances and automobile air conditioning seventy years prior. As a result, it’s quite unusual that you’ll come across an R12 appliance in your home. However, R12, which was withdrawn in 1996, can still be found in automobiles produced earlier to that year.

Why was refrigerant R12 banned?

The ozone layer is harmed by the chlorine present in R12. R12 was outlawed in order to slow the growth of the greenhouse effect, and R134a was selected as a substitute.

Is R12 colder than R134a?

According to certain studies, R12 is 6 to 7 degrees colder and 15% more efficient than R134a in some applications. The fact that it is now prohibited and nearly impossible to obtain doesn’t matter much.

How do you convert a refrigerator from R12 to R134a?

Go back up and study the necessary steps and tools for converting an R12 system to R134a. Recharging the refrigerant, on the other hand, will prove to be a difficult operation.

How much will it cost to convert R12 to R134a?

A mechanic will charge you around $200 for the conversion alone, but you can do the job yourself for the same amount and keep the tools you’ve bought. For between $150 and $500, you can recharge your AC, but that’s worth it because poorly charging your AC can cause much more expensive harm.

Why Does My Car Idle Rough When I Turn On The AC?

A faulty AC compressor or throttle control are the most likely culprits behind your car’s choppy idle when the AC is on.


Even though the R12 refrigerant has been completely phased out, there are still ways you can get the AC to run at full blast. A retrofit to R134A coolant is not expensive and can be handled at home. As for the coolant recharge, I would not advise you to do it yourself, but if you’re confident, get the right tools and do it.