As R-12 continues to disappear, the price of R-12 refrigerant continues to rise. So what do you recharge an older air conditioning system with if R-12 is unavailable? DROP-IN ALTERNATIVES FOR R-12 REFRIGERANT? Though a number of alternative refrigerants are marketed as "drop-in" replacements for R-12, there is really no such thing as a true drop-in replacement. The reason why is because Federal law prohibits the topping off A/C systems with ANY refrigerant that is chemically different from what is already in the system, unless all of the old refrigerant is first removed so the system can be converted to the alternative refrigerant. There are, however, a number of alternative refrigerants that can be used in older vehicles with R-12 A/C systems, and most have been reviewed and approved by the EPA for retrofitting older R-12 A/C systems. Approved refrigerants must meet the EPA's SNAP (Significant New Alternatives Policy) criteria for environmental acceptability and usage. NOTE: The SNAP rules prohibit the use of flammable refrigerants (propane, butane and similar hydrocarbons) in mobile A/C systems because of their hazardous nature, and the SNAP rules prohibit the use of any other refrigerants that contain ozone-damaging CFCs. for more information about flammable refrigerants, Click Here. APPROVED ALTERNATIVE REFRIGERANTS FOR AUTOMOTIVE USE There are number of alternative refrigerants from which to choose. One is R-134a, which is the ONLY alternative refrigerant currently approved by all vehicle manufacturers for retrofitting older R-12 A/C systems. The vehicle manufacturers say R-134a will cool reasonably well in most R-12 A/C systems provided the proper retrofit procedures are followed. They also recommend R-134a because it is a single component refrigerant, unlike most of the alternatives which are actually BLENDS of two to more ingredients. The vehicle manufacturers do not like blends because blends can undergo "fractionation." This is when the individual ingredients in a blend separate for various reasons. Fractionation can be caused by chemical differences between the refrigerants (lighter and heavier elements do not want to stay mixed), different rates of leakage through seals and hoses (smaller molecules leak at a higher rate than larger ones), and different rates of absorption by the compressor oil and desiccant. Fractionation is a concern because it can change the overall composition of the blend once it is in use, which can affect the performance characteristics of the refrigerant. Fractionation also makes it difficult to recycle a blended refrigerant because what comes out of the system may not be the same mix that went into the system. If you would like to read a variety of different views on the subject of alternative refrigerants and retrofits, Click here. The vehicle manufacturers also say limiting the alternatives to one choice (R-134a) simplifies things, reduces the risk of cross-contamination and eliminates the need for multiple recovery machines. EPA rules require a separate dedicated recovery only or recovery/recycling machine for each type of refrigerant serviced. ALTERNATIVE REFRIGERANT BLENDS Alternative refrigerants that have been found acceptable for automotive applications or are currently being reviewed by the EPA include the following blends: Free Zone (RB-276). Supplied by Refrigerant Gases, this blend contains 79% R-134a, 19% HCFC-142b and 2% lubricant. Freeze 12. Supplied by Technical Chemical, this blend contains 80% R-134a and 20% HCFC-142b. FRIGC (FR-12). Made by Intermagnetics General and marketed by Pennzoil, this blend contains 59% R-134a, 39% HCFC-124 and 2% butane. GHG-X4 (Autofrost & McCool Chill-It). This blend is supplied by Peoples Welding Supply and contains 51% R-22, 28.5% HCFC-124, 16.5% HCFC-142b and 4% isobutane (R-600a). GHG-HP. Also supplied by Peoples Welding Supply, this blend contains 65% R-22, 31% HCFC-142b and 4% isobutane (R-600a). Hot ShotKar Kool. Supplied by ICOR, this blend contains 50% R-22, 39% HCFC-124, 9.5% HCFC-142b and 1.5% isobutane (R-600a). The suppliers of the alternative blends say their products typically cool better than straight R-134a in systems designed for R-12, and do not require changing the compressor oil or desiccant in some cases. Changing the desiccant to XH-7 is usually recommended if an R-12 system is converted to R-134a. The desiccant should also be replaced if a blend contains R-22 because R-22 is not compatible with XH-5 or XH-7 desiccant. The recommended desiccant in this case would be XH-9. The suppliers of the alternative blends also insist the fractionation problem is exaggerated and do not foresee any major problems with recovering and recycling their products (recycling blends is currently illegal, but the EPA is reviewing its feasibility). One supplier of these products say they sold several million pounds of their alternative refrigerant, so the public is accepting it. MACS ALTERNATIVE REFRIGERANT FIELD STUDY A field study of various refrigerants conducted by the Mobile Air Conditioning Society (MACS) compared the cooling performance of R-12, R-134a and three blended refrigerants (Freeze 12, FRIGC and McCool Chill-It). The study found that all the alternative refrigerants (including R-134a) did not cool as well as R-12 in the vehicles tested (a 1990 Pontiac Grand Am and a 1987 Honda Accord). But the study did find that the blends outperformed R-134a in the Honda (but not the Pontiac). The increase in A/C outlet temperature with the different refrigerants ranged from less than a degree to almost 11 degrees. ILLEGAL REFRIGERANTS Another class of alternative refrigerants has also appeared on the scene: illegal refrigerants. Some products that have been introduced (OZ-12, HC-12a, R-176 and R-405a) do not meet the EPA criteria for environmental acceptability or safety. Flammable refrigerants such as OZ-12 and HC-12a that contain large quantities of hydrocarbons (propane, butane, isobutane, etc.) have been declared illegal for use in mobile A/C applications, but are still turning up in vehicle systems anyway because of their cheap price. WARNING: Flammable refrigerants pose a significant danger to the occupants inside a vehicle should a leak occur. A spark from a cigarette or a switch can ignite the leaking refrigerant causing an explosion and turning the car into a bomb. It only takes about four ounces of a flammable hydrocarbon refrigerant such as propane or butane to create an explosive mixture inside a typical automobile passenger compartment. Frontal collisions can also release the refrigerant if the condenser is damaged, which could result in a severe underhood fire causing extensive damage to the vehicle. There is also a risk to service technicians and do-it-yourselfers who might encounter leaks while servicing a vehicle or operating recovery/recycling equipment. Merely topping off an A/C system with a flammable hydrocarbon can make the entire charge of refrigerant flammable if the amount added exceeds a certain percentage: 10% in the case of an R-12 system and only 5% with R-134a! That is only three or four ounces of hydrocarbon depending on the overall capacity of the system. Flammable refrigerants are used in some stationary applications as well as truck trailer refrigeration units because there is less risk of leakage or fire. Also, the amount of refrigerant is typically much less, only five or six ounces total instead of several pounds. BOOTLEG REFRIGERANTS Less dangerous but equally illegal is bootleg R-12 that is being smuggled into the U.S. from offshore. Though most of the industrialized nations have stopped manufacturing R-12 (production ended in the U.S. December 31, 1995), R-12 is still being made in some Third World countries including Mexico. Some of this product is finding its way past customs in mislabeled containers or concealed in various ways. The EPA warns that much of the refrigerant it has confiscated thus far is of poor quality, contaminated by air, moisture, R-22 and other substances. The EPA has worked with customs authorities and the FBI to make a number of arrests. Fines for violating the clean air rules can run up to $25,000 per instance. Counterfeiting branded product is another scam that is being perpetrated to turn a fast buck in today's market. Cylinders of counterfeit Allied Signal Genetron R-12 have reportedly been turning up in various parts of the country. The cylinders do not contain R-12 but some "unknown" refrigerant. Allied Signal says the counterfeit boxes do not have cut-outs where lot numbers strapped on cylinders would appear and there are no bar codes or white painted stripes on the sides. The number "Q 1167" may also appear on the bottom of the packaging. The cylinders themselves may be marked with a pressure-sensitive decal whereas the genuine product has markings printed on the cylinder itself. CONTAMINATED REFRIGERANT The high price of automotive refrigerants (R-12, R-134a and R-1`234yf) has also lead to an increase in incidences of virgin refrigerant being adulterated with other less expensive refrigerants and chemicals (such as propane, butane, etc.). Most technicians assume a tank of virgin refrigerant is pure and safe to use, but some are finding that is not the case. Some suppliers say they now test every single tank of refrigerant to make sure it contains the proper refrigerant and that the quality of the refrigerant meets specifications. Many repair shops and car dealers also use a refrigerant identifier to check the quality and purity of the refrigerant they buy. The primary threat of contamination, though, is that of accidentally cross-contaminating refrigerants when vehicles are professionally serviced. Because the law requires all refrigerants to be recovered, there is a potential risk of contaminating when recovery and recycling equipment is connected to a vehicle. The problem is compounded, many say, by the proliferation of alternative and illegal refri…

Fonte: AA1Car.com