Refrigerant: Fundamentals and Basics

Commercial Designation:
The following designations are used and appear on component labels and factory tags:
- R-134a
- Tetrafluoroethane
- CH2F CF3
- H-FKW 134a
- SUVA(R) TRANS A/C
- ARCTON(R) 134a

NOTE: R-134a refrigerant is packaged in different containers. One variation is SUVA(R) COLD MP, used only for commercial applications. This type of R-134a is sold in cylinders using a 1/4 inch flare fitting, which will not connect to the 1/2 inch-16ACME fittings used on the vehicle and servicing equipment. Use only R-134a which come in containers having the correct type of service fitting.

Color:
Refrigerant R-134a is colorless and is invisible as a gas. R-134a when viewed through the sight glass may appear milky due to the mixture of refrigerant and lubricating oil (PAG oil).

Temperature/Pressure Relationship:
Similar to R-12 refrigerant, R-134a in an enclosed container will have a specific temperature/pressure relationship as follows:

Temperature in °C (°F) Pressure in bar (psi)
-30 (-22) 0.0 ( 0.0)
-20 ( -4) 0.3 ( 4.4)
-10 ( 14) 1.0 ( 14.5)
0 ( 32) 1.9 ( 27.5)
10 ( 50) 3.1 ( 45.0)
20 ( 68) 4.7 ( 68.2)
30 ( 86) 6.7 ( 97.2)
40 (104) 9.1 (132.0)
50 (122) 12.2 (177.0)
60 (140) 15.8 (229.2)
70 (158) 20.2 (293.0)

Refrigerant Oil:
A special Polyalkylene Glycol (FAG) synthetic oil is used in R-134a systems. This oil is NOT compatible with mineral based oils used in R-12 systems. [1][2]Service Precautions for Warnings and Cautions regarding proper oil usage.

Airborne Properties:
Escaped refrigerant gases are heavier than air and will gather first in low places, such as underneath the car. R-134a refrigerant gas displaces oxygen and may cause suffocation in low areas of poor air circulation.

Effects on the Environment:
Because R-134a does not contain chlorine atoms, the major catalyst in ozone depletion, R-134a has no ozone depletion potential.

R-134a does not cause smog and has a considerably lower global warming potential (greenhouse effect) than R-12 refrigerant. Nonetheless, do not release R-134a into the environment and always recover/recycle using approved service equipment.

Effects on Plastics:
Refrigerant R-134a will deteriorate some plastics. When system temperature drops, these plastics can be deposited at the expansion valve or restrictor causing blockage. Therefore, when making system repairs, use only genuine VW replacement parts which are specified for use with the R-134a refrigerant.

Effects on Metal:
In its pure state, refrigerant R-134a is chemically stable and will not attack iron, copper, brass or aluminum. However, the mixture of R-134a and PAG oil may deteriorate certain metals (copper), which could lead to blockage, leaks or deposits on the compressor piston. Therefore, when making system repairs, use only genuine VW replacement parts that are specified for use with R-134a refrigerant.

Water Solubility:
Liquid R-134a refrigerant will absorb only very minute quantities of moisture. However, R-134a vapor can absorb large amounts of moisture.

Water in the System Forms Ice in the Expansion Valve or Restrictor causing the system to stop cooling. In addition, moisture combines with the refrigerant to form acids which will damage the system.

Toxicity:
Refrigerant R-134a is non-toxic up to a temperature of 101 °C (214 °F) and is safe when handled and used properly.

Above 101 °C (214 °F), gas pressure is above 39.5 bar (573 psi) and R-134a begins to decompose into poisonous gases (hydrogen fluoride, carbonyl fluoride and fluorine). These gases give adequate warning of their presence since they cause irritation of the mucous membrane (throat).

Refrigerant R-134a gas has no effect on foodstuffs; it does not poison food or make it inedible.

Flammability:
R-134a refrigerant is not flammable. In fact, it tends to inhibit combustion and has a fire extinguishing effect. However, a flame or glowing hot surface, as well as ultraviolet light (from electric welding), will decompose the refrigerant into poisonous gases (hydrogen fluoride, carbonyl fluoride and fluorine). These gases give adequate warning of their presence since they cause irritation of the mucous membrane (throat).

R-134a can become flammable at pressures above ambient pressure in conjunction with air concentrations greater than 60% by volume.

Refrigerant Containers:
DO NOT exceed maximum rated capacity of refrigerant containers. Never fill a container to more than 60 % of its gross weight rating (for example, 18 lb in a 30 lb container).

Without sufficient room for expansion of R-134a (gas cushion), the container could explode when the temperature rises causing serious injury.

Leak Detection:
Use halogen leak detector Hitec HI400A-TEL or equivalent to check for R-134a system leaks. This tool can also be used to detect leaks in R-12 systems. Many currently available R-12 leak detectors cannot detect R-134a refrigerant leaks.

R-134a refrigerant oil:
A special Polyalkylene Glycol (PAG) synthetic oil is used in R-134a systems. This oil is NOT compatible with mineral based oils used in R-12 systems.