Refrigerant Differences

R12(Freon) and R134a are not compatible and must never be mixed. R134a is less efficient than R12. Higher operating pressures and larger system components make up for the difference in performance. Leakage is of greater concern with R134a because its molecules are smaller than those of R12 and it can seep through the rubber hoses more easily. R134a mixed with high-pressure air can be ignited under certain conditions by a spark or open flame. R134a is an irritant and also very corrosive. It will tarnish and discolor any metal with which it comes in contact in liquid form.

R12 is highly toxic when exposed to flame. The product of its combustion is phosgene gas, a powerful irritant to human tissue. R12 gas released into the atmosphere rises to the stratosphere where it can linger for decades. In the stratosphere, a layer of ozone acts as a sunscreen that protects Earth from the sun's ultraviolet rays. The R12 reacts with the ozone to produce compounds that cannot filter the sunlight, allowing more ultraviolet radiation to reach Earth. More ultraviolet rays can cause increase in skin cancer, more eye cataracts, reduced immunity to disease, damage to vegetation, and increased amounts of ozone at ground level where smog is formed.