Things are heating up in the world of mobile a/c service. While discussions on the next possible refrigerant continue, service equipment designed to work with the current refrigerant and meet the newest SAE standards is now available.
The world of auto air conditioning sendee is in the middle of a sea change, and the 2008 Mobile Air Conditioning Society (MACS) convention and trade show held in January of this year was dotted with examples.
There's a lot to talk about, of course. In this report we'll tell you about a couple of new refrigerant blends that show some promise for success, new R-134a equipment that has found its way to the marketplace, a new generation of leak detectors and a bevy of new tools and kits designed to make a/c service easier and faster. Let's get right to it.
The Next Refrigerant
Although R-134a is still the U.S. refrigerant for the foreseeable future, the Europeans are close to a legally mandated phaseout, which is less than three years away. Will cars they produce for export to the U.S. come with a new refrigerant, or might the Europeans do a crash engineering job to design their vehicles to accommodate two totally different systerns able1 to come down the same vehicle final assembly lines? We don't know because they don't know. Reports say there still are no firm contracts signed for components and chemicals for any alternative to R-134a.
All the blend refrigerants that were considered alternatives have fallen victim to toxicity and other issues. There are still the likely very expensive highpressure carbon dioxide refrigerant systems. And there's R-152a, a mildly flammable refrigerant, which would require an underhood-only system (with a separate, liquid coolant heat exchange to the underdash system). And use of this refrigerant raises some packaging issues.
Recently emerging as a new choice is HFO-1234yf, the primary ingredient in a previous blend, Fluid H, by Honeywell. Taking out the second ingredient, a fire retardant but also a cardiac sensitizer among its issues, means that HFO-1234yf alone raises flammability questions. Rut tests show its flammability is far less significant than that of R-152a, and so it could be circulated through an underdash evaporator, same as an R-134a system. HFO-1234yf takes so much ignition energy to set aflame, it cannot be ignited with a butane lighter or even an arc welder, according to DuPont and Honeywell, who are in a joint venture to commercialize this refrigerant. Toxicity testing to date has produced good results, they said, and performance testing shows it's slightly more efficient than R-134a. Direct circulation to an underdash evaporator saves one level of heat exchange, which has cost, packaging and efficiency advantages.
HFO-1234yf has a pressure-temperature curve almost identical to that of R-134a, and any system leaks reportedly could be found with current R-134a electronic detectors. The new refrigerant's appeal? Its global warming number is just 4, well below the European regulatory limit of 150, and far below that of R-134a, which is 1200. Although HFO-1234yf is not quite a drop-in replacement for R-134a, it's close enough so that major system changes would not be necessary. However, the flammabiliry issue, although minor, might mean that a safety venting system for HFO-1234yf would be needed, such as sensors to detect any leakage from the evaporator, and electronics to instantly open valves to vent the refrigerant charge to the atmosphere.
The German manufacturers have verbally committed to producing carbon dioxide (COz) refrigerant systems, and continue to develop them. In meetings with equipment makers prior to the MACS show, they worked to ensure that, if CO2 is chosen for production, electronic leak detectors and recovery/recharge equipment would be available for service. Because it has a global warming number of just 1, CO2 would not have to be recycled (a similar decision for HFO-1234yf, if it's used, would be premature at this point). Because we inhale air and exhale CO2, technicians apparently would have to wear a mask while using a leak detector.
Other European makers, including fiat, Renault and Peugeot-Citroen, have cited major issues with CO2. General Motors is hedging bets, with a mild commitment to CO2 but an indicated readiness to use HFO-1234yf, if it's deemed feasible.
A choice of a new refrigerant for European cars should already have been made, to ensure enough time with production-level components to integrate a new a/c system into new models and perform field tests. Carbon dioxide is furthest along in development, but because a CO2 system poses cost and remaining reliability issues, HFO-1234yf still could make it. Or, as seems very possible, European carmakers could split, some going for COz, the others for HFO-1234yf. A decision by this summer seems certain, but we also thought we'd know a year ago.
We can reasonably say this: If CO2 is used as a refrigerant by any makers, they surely would prefer to install it only in models for the legally mandated European market for at least a year or two. Recognizing the CO2 reliability questions, the last thing the makers want to do is have to perform factory fixes for such new technology on export models. The European law requires an alternative to R-134a only in new models, not in what largely are carryovers.
