One problem that’s developed as substitutes for R-12 have been tried is the “chemical soup” created by the blending of various types of dissimilar and incompatible products marketed as refrigerants.

“It sets up a very advanced corrosion that’s faster than even a salt-spray corrosion test,” explains Al Sedita, owner of Classic Auto Air in Tampa, Florida. “The EPA approves refrigerants from a toxicity standpoint, not performance or longevity. There have been about a dozen approved by EPA as alternative refrigerants, but that does not mean that they’re good, safe, and efficient to use in an automotive air conditioner.” In fact, many of these substitutes are legal replacements only in industrial or commercial applications, and not automotive. “About the time these products were hitting the market, we also saw oil additives introduced that claimed to not only increase system longevity, but make the system colder, some claimed by as much as 8-10 degrees,” says Al. “But tests done by some of the compressor and O-ring manufacturers show that there’s a cross-contamination situation that can create compressor failure in months rather than years.”

When R-12 began to be subject to sales restrictions, some auto parts stores began to put R-22—a refrigerant used in household refrigerators and central air conditioners—on that same spot on the shelf. Al says, “We saw a lot of hobbyists use it, then their system doesn’t work right, so they go to a shop that doesn’t have refrigeration identification equipment and it gets sucked into their refrigerant recovery machine. Some other guy comes in and he’s got some other refrigerant. Before you know it we’ve got “chemical soup” in that recovery machine that gets put into 20 or 30 other cars. Then those cars have problems and they go to a different shop and the contamination begins to snowball.”

Refrigerant identifier technology has improved, and now most bigger shops use them. But manufacturers of parts, seals, and O-rings will not warranty their products for any refrigerant other than R-12 or R-134a. That includes oil additives.

Stick with industry-approved products and your system will hold up—and stay cool—over the long haul.