Passat Wagon V6-2792cc 2.8L DOHC (1994)
Refrigerant: Description and Operation
A/C Refrigerant R-134a, Properties
Commercial designation
Obtain R-134a refrigerant from a local A/C supplier under one of the following names:
- R-134a
- Tetrafluoroethane
- CH2FCF3
- H-FKW 134a
- Suva® TRANS A/C
- ARCTRON® 134a
Note: R-134a refrigerant is packaged in different containers. One variation is Suva® COLD MP used only for commercial applications. This type of R-
134a is sold in cylinders using a 1/4 flare fitting which will not connect to the 1/2-16 ACME fittings used on the vehicle and servicing equipment. Use
only R-134a which comes in containers having the correct service fitting.
Color
Refrigerant 134a is colorless and invisible as a gas. R-134a, when viewed through a sight glass (if installed) may appear milky because of the mixture of
refrigerant and lubricating oil (PAG oil).
Temperature and pressure relationship
Similar to R-12 refrigerant, R-134a in an enclosed container will have a specific temperature and 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 (PAG) synthetic oil is used in R-134aSystems. This oil is not compatible with mineral-based oils used in R-12 systems.
See safety measures for WARNINGS and CAUTIONS regarding the proper use of refrigerant oil. See: Heating and Air Conditioning/Service
Precautions
Airborne properties
Escaped refrigerant gases are heavier than air and will gather first in low places, like under a car. R-134a refrigerant gas replaces 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, it has no ozone depletion potential.
R-134a does not cause smog and has considerably lower global warming potential (greenhouse effect) than R-12 refrigerant. Nonetheless, do not release
R-134a into the environment and always recover and recycle refrigerant using approved service equipment.
Effects on plastics
Refrigerant R-134a will deteriorate some plastics. When the system pressure drops, these plastics can be deposited at the expansion valve or restrictor
causing blockage. Therefore when making system repairs, use only genuine Volkswagen replacement parts which are specified for use with R-134a
refrigerant.
Effects on metal
In its pure state, refrigerant R-134a is chemically stable and will not attack iron or aluminum. However a 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 Volkswagen replacement parts which 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.