In vehicle air conditioning systems, the R12 and R134a are the two most common types of refrigerant gases. All the cars that are made after 1994 come with the R134a cooling system. All the cars that are made before 1994 come with the R12 cooling system. Owing to this, vehicle owners of old models who have the R12 refrigerant system tend to use a conversion chart to convert to R134a.
The R12 to R134a conversion chart is for converting the air conditioning system of the vehicle according to the operating condition and refrigerant type. It enables adjusting the charge accordingly and it is also suitable for HVAC equipment.
R12 to R134a Charge Conversion Formula
The conversion of R12 to R134a refrigerant is according to a formula. Applying this formula will convert the value of the original R12 charge to the R134a charge.
You can begin the formula in pounds by multiplying the R12 charge value by .75. When the scales are in point story .25 or .5 increments, it is adjusted to the highest quality.
The other method will be by multiplying the R12 charger specification by 0.9 and subtracting 0.25 lbs. This helps to provide the correct R134a charge. Here is an example of the same.
If the R12 charge value is 3 lbs.
It will be (R12 charge specification x 0.9) – 0.25 lbs.
= (3 x 0.9) – 0.25 lbs.
= 2.45 lbs.
The charge level of 3 pounds of R12 will be 2.45 lbs. of R134a.
R12 to R134a Refrigerant Charge Conversion in pounds (lbs)
| R12 Charge Specification | R134a Refrigerant Charge Level | R12 Charge Specification | R134a Refrigerant Charge Level |
| 1 lb. | 0.65 lbs. | 1.5 lbs. | 1.1 lbs. |
| 2 lbs. | 1.55 lbs. | 2.5 lbs. | 2 lbs. |
| 3 lbs. | 2.45 lbs. | 3.5 lbs. | 2.90 lbs. |
| 4 lbs. | 3.35 lbs. | 4.5 lbs. | 3.8 lbs. |
| 5 lbs. | 4.25 lbs. | 5.5 lbs. | 4.7 lbs. |
| 6 lbs. | 5.15 lbs. | 6.5 lbs. | 5.6 lbs. |
| 7 lbs. | 6.05 lbs. | 7.5 lbs. | 6.5 lbs. |
R12 to R134a Refrigerant Charge Conversion in Ounces (oz)
| R12 Charge Specification | R134a Refrigerant Charge Level | R12 Charge Specification | R134a Refrigerant Charge Level |
| 3 oz. | 2.3 oz. | 3.5 oz. | 2.6 oz. |
| 4 oz. | 3 oz. | 4.25 oz. | 3.2 oz. |
| 4.5 oz. | 3.4 oz. | 4.75 oz. | 3.6 oz. |
| 5 oz. | 3.8 oz. | 5.25 oz. | 3.9 oz. |
| 5.5 oz. | 4.1 oz. | 5.75 oz. | 4.3 oz. |
| 6 oz. | 4.5 oz. | 6.25 oz. | 4.7 oz. |
| 6.5 oz. | 4.9 oz. | 6.75 oz. | 5 oz. |
| 7 oz. | 5.3 oz. | 7.25 oz. | 5.4 oz. |
| 7.5 oz. | 5.6 oz. | 7.75 oz. | 5.8 oz. |
| 8 oz. | 6 oz. | 8.5 oz. | 6.4 oz. |
| 9 oz. | 6.8 oz. | 10 oz. | 7.5 oz. |
| 11 oz. | 8.3 oz. | 11.5 oz. | 8.6 oz. |
| 12 oz. | 9 oz. | 12.5 oz. | 9.4 oz. |
| 13 oz. | 9.8 oz. | 13.5 oz. | 10.1 oz. |
Conclusion
The R12 to R134a conversion chart serves great for old vehicle models. By applying the above formula, you will be able to have the accurate R134a charge. You can easily do it for both lbs and oz. Enter the appropriate R12 charge specification in the formula which will provide the correct R134a refrigerant charge level.
