Then concerns about ozone depletion and global warming drove the world to the Montreal Protocol Treaty, which has been signed by the United States, and over 150 other countries. Among its other provisions was a general agreement to stop using chlorofluorocarbons (CFCs) wherever possible.

Freon, the brand name for chlorofluorocarbon known generically as R-12 or CFC-12, became a target of the Clean Air Act, which was written in part to implement the provisions of the Montreal Protocol. The Clean Air Act is implemented through regulations that are developed, promulgated, and enforced by the U.S. Environmental Protection Agency (EPA).

Through such regulations, use of R-12 in mobile and stationary air conditioning systems and refrigeration units was ordered phased out, and all production in the U.S. for those purposes stopped as of December 31, 1995. The R-12 being used now to service existing mobile air conditioning systems must come from manufacturer stockpiles, distribution system and vehicle manufacturer inventories, and recycled product.

Once vehicle and A/C system manufacturers knew they couldn't use R-12 forever, they began the search for a substitute. They researched and tested a wide variety of potential R-12 substitutes, reviewing the potential health effects, toxicity, flammability, corrosive potential, cooling performance, durability, and affect on the expected life of A/C system components for each one.

The eventual winner became R-134a. This chemical, an ozone-friendly hydrofluorocarbon (also abbreviated HFC-134a), has been universally chosen by vehicle makers worldwide as the R-12 substitute of choice.

With the phase-out of R-12 imminent, some R-134a systems were put into selected new passenger car and light truck models as early as 1992, and by 1994 all new mobile A/C systems had been converted to the new refrigerant. But the world of mobile A/C systems has not remained so simple that you can simply determine whether a vehicle contains R-12 or R-134a, and service it with the appropriate one.

Section 612 of the Clean Air Act requires the EPA to establish a program to identify alternatives to Class I and Class II ozone-depleting substances. In response it had developed its Significant New Alternatives Policy. The SNAP program serves to identify and categorize proposed alternative refrigerants as "acceptable subject to use conditions," "acceptable subject to narrowed use limits," or "unacceptable" based on their "overall risks to human health and the environment." In the automotive world, SNAP refrigerants are substitutes for R-12 (a Class I substance).

Anyone who produces a substitute must provide EPA with health and safety studies, and notify the agency at least 90 days before introducing it into interstate commerce. According to the EPA, "this requirement applies to chemical manufacturers, but may include importers, formulators or end-users when they are responsible for introducing a substitute into commerce."

The real problem for aftermarket distribution and retail operations is that it is not illegal to sell alternative refrigerants before the EPA has ruled on whether they are acceptable or not, but it is illegal to use one that has been declared "unacceptable" (charging it into a customer's A/C system is considered a use), and the penalties can be fines up to $25,000 per day and five years in jail.

Therefore, if the EPA takes longer than the 90 days of required pre-notification to make its determination, manufacturers (or importers or others) could begin to sell substitute refrigerants that might ultimately be declared unacceptable. Once the declaration of unacceptability is made, obviously, the market will dry up like Death Valley in August, and your outlet could be left holding unsellable (and perhaps unreturnable) inventory.

From a commercial standpoint, it is prudent to stock only R-134a or other declared "acceptable" SNAP substitutes, and leave the "proposed" products alone until the EPA had made a declaration one way or another.

For the EPA, concern about substitute refrigerants can end with a declaration of acceptability or unacceptability. Unfortunately, that is not the case for the counter professional.

Why is our burden heavier than that of the EPA? Because the law only requires the EPA to determine that a product is or is not acceptable, based on its "overall risks to human health and the environment." They make no determination about how it will perform in a vehicle's air conditioning system.

That's right. Just because a substitute chemical is declared acceptable doesn't mean it will actually cool the interior of the vehicle on a hot day, or refrain from corroding the insides out of the system components, or that it is compatible with the lubricants in the system, or that it is safe under every possible condition.

In order for customers to get the quality of service they expect, you have to be able to give them some guidance on the performance aspects of the substitute refrigerants your outlet may decide to carry. And you will have to obtain that from manufacturers, independent testing labs, or organizations like the Mobile Air Conditioning Society (MACS), Broomall, PA, or the International Mobile Air Conditioning Association (IMACA), Fort Worth, TX.

Please note that this is not meant to imply that all SNAP refrigerants perform poorly even if rated acceptable, but rather to caution you that a stamp of "acceptable" from the EPA has a limited meaning that you must be aware of.

In no case can any SNAP refrigerant -- even an acceptable one -- be used to top off a system that has another type of refrigerant in it. While some manufacturers are marketing their SNAP products as "drop-in" replacements for R-12, this indicates only that that chemical manufacturer believes this chemical will work with the same system components and hoses as were used when the system operated on R-12. (We'll discuss this more under the heading Retrofit Concerns, below.) The mixing of two different refrigerants in a vehicle's system is strictly forbidden because of its risk to the system integrity and safety, as well as its impact on recycling.

One of the biggest problems generated by the phase-out of R-12 comes from the fact that, while the newest vehicles on the road use the acceptable, ozone-friendly R-134a, the far larger percentage of cars and light trucks still in the national fleet were manufactured in the days of cheap and available R-12, and that's exactly what their A/C systems are charged with.

Since R-12 from old vehicle A/C systems cannot be released to the atmosphere without potentially increasing stratospheric (upper atmosphere) ozone depletion, and since we need large quantities of R-12 to service the existing fleet, recycling has been mandated. In fact, recycling is required not only of R-12, but of R-134a and any other substitute refrigerant that is now or may become approved for use in mobile A/C systems.

The problem arises not so much from requiring recycling, but from the fact that each refrigerant must be recycled separately. That means an exclusive recycling/recovery unit at each service location, for each type of refrigerant that that service location might encounter. No two refrigerants may be mixed in the same recycling equipment.

If one refrigerant were to be accidentally introduced into a batch of another refrigerant, the entire contaminated lot would become a waste disposal migraine, and the recycling equipment would have to be purged and cleaned as well.

With only R-12 and R-134a being used by the vehicle original equipment manufacturers (OEMs), that would seem to make the recycling problem a relatively simple one.

Unfortunately, while these two refrigerants are the only ones installed in new vehicle A/C systems, the use of SNAP refrigerants, especially in older vehicles, will eventually lead to the presence of a number of different refrigerants sprinkled among the cars and light trucks on America's highways.

The tough questions whether customers will be able to get service for the SNAP refrigerants that are sold, or be able to find supplies of the same refrigerant if the system should need topping off after initial charging.

To help assure that different refrigerants are not inadvertently mixed, each vehicle A/C system must have special service fittings installed that are unique for that refrigerant, and a color-coded label must be applied under the hood, identifying the type of refrigerant installed in the system.

If you stock R134a, or any SNAP refrigerants, check to make sure you also stock the appropriate fittings and labels, because customers are likely to need them.

Replacing R-12 with R-134a or a SNAP product is commonly referred to as a retrofit. You may have read some horror stories early on about the costs and complexity of retrofitting a vehicle A/C system for R-134a. It turns out that most retrofits will not be too expensive or too complex, though requirements vary by vehicle make and model.

In its "Guidance on Retrofitting," the EPA notes two types of retrofits: OEM retrofits, and Least Cost Aftermarket retrofits. The OEM retrofits, based on OEM-developed guidelines and kits, result in performance essentially equivalent to that obtained using R-12 and generally qualify for an OEM warranty. Cost is estimated from about $150 to over $650, depending on the make, model, and prevailing regional labor rates. OEM retrofit kits and guidelines are usually available only for late '80s and early '90s model vehicles.

Aftermarket retrofits must be used for vehicles built before the late '80s. These retrofits can also be done much less expensively than the OEM retrofits, though performance in all vehicles may not be as good as when the vehicle operated on R-12. The aftermarket retrofit, as defined by the EPA, would require "removal of the old refrigerant, installation of new service fittings and a new label (a legal requirement for all retrofits), and the addition of either a polyalkylene glycol (PAG) or polyol ester (POE or ester) lubricant as well