Air Conditioning Fundamentals
TC070-05-01S
7 – REFRIGERANTS
50
In the mid-1980s, scientists discovered that chemicals called
chloro-fluorocarbons (CFCs) were destroying the ozone in the
atmosphere. Ozone protects the earth from harmful ultraviolet rays
released by the sun.
One of the major contributors to CFCs in the atmosphere was R-12,
which often leaked into the atmosphere during servicing of A/C systems.
In 1987, the United States and 22 other countries signed an
international agreement calling for the gradual phase-out of CFCs.
In 1990, the United States revised the federal Clean Air Act, adding
stricter CFC standards than the international agreement. As a result,
R-12 was phased out of most automotive A/C systems in about 1990.
By the year 2000, R-12 will be banned completely.
HFC134a (R-134a)
Because of the environmental damage caused by R-12, scientists
developed an alternative refrigerant called R-134a. Most vehicles
manufactured from 1990 to the present use R-134a as an A/C
refrigerant.
Chemical Structure
R-134a is the common name for Tetrafluoroethane-134a (HFC-134a),
whose chemical formula is CH2FCF3. Unlike R-12, R-134a does not
contain CFCs. Instead, it contains hydrofluorocarbons (HFCs), which do
not damage the ozone layer.
Figure 29 shows the chemical structure of R-134a, which contains two
carbon atoms, two hydrogen atoms, and four fluorine atoms.
FIGURE 29. R-134
contains carbon,
hydrogen, and
fluoride atoms. It is
used as a refrigerant
in most vehicles built
from 1990 to the
present.