The Cold Standard

By law, every R&R machine sold – new or used – must be certified that it meets the SAE standard J2210. In December, SAE announced the new J2788 standard that defines the new performance requirements for R&R equipment. EPA is planning to update its rules too by requiring shops to purchase only those machines meeting the new standard.

However, the rulemaking process takes time, and EPA's Dr. Steven Anderson told Motor Age that at this point, "SAE is requiring that the equipment cannot be labeled to the old standard after December [2007]. Implementation of [upgrading equipment] in the market is being accomplished by the SAE standard," meaning this upgrade is not driven by EPA rules. The Agency's rules will eventually be updated, but Dr. Anderson said it will take at least several months.

After that date, any shop purchasing service bay R&R machines must purchase new equipment that meets J2788 standards in order to obtain Section 609 Certification that's required to be in the air conditioning (A/C) service business. Dr. Anderson pointed out that shops will not be required to replace existing equipment, saying that "EPA absolutely favors voluntary programs. We don't intend to go out and sweep up obsolete equipment, but we do intend to create incentives for the equipment to be retired."

To summarize, beginning in December 2007, only the equipment meeting the new specifications will be manufactured. At some later date in 2008, shops will be allowed to buy only this new-spec equipment (new or used), but no one will be forced to stop using their existing equipment.

Instead, EPA is looking for ways to make it attractive for shops to retire older specification equipment sooner and switch over to the new machines. During the press conference, Dr. Anderson mentioned the word "rebate" and suggested funding could possibly come from the Chicago Climate Exchange. While this statement was speculation, it was intended to show that the Agency is actively searching for incentives for shop owners to upgrade to the new A/C service equipment.

EXPECT TO PAY MORE

Berdan said that "the technology that's required to meet these new standards is expensive," and pointed out the new machine will retail for approximately $500 more than its previous top-of-the-line model. He described some of the requirements called for by the new specifications, saying that the machine:

1. Must recover 95 percent of the refrigerant in 30 minutes.

2. Must have a charge accuracy of ±0.5 ounce.

3. Must lock-out the user when filter service is required.

4. Must minimize cross-contamination when switching from one oil to another.

Berdan also explained that the machine includes an on-board computer and database that allow the machine to be operated in a fully automatic mode. While these are optional features, the lock-out requirement makes it likely that software and computer controls will be required on all new R&R machines, accounting for at least part of the cost increase. The other major cost factors are the new hardware needed to meet the recovery and charge accuracy specifications.

CERTIFICATION

In the certification lab, the R&R machine will be weighed on a special scale with a resolution of ±1 gram. After the machine's starting weight is recorded, the hoses are connected to the test A/C system and the refrigerant charge is recovered. Then the hoses are disconnected and laid across the top of the machine, and the final weight is recorded. Because the weight of the refrigerant in the test A/C system is known, the refrigerant in the machine's holding tank and hoses equals the amount recovered from the test A/C system.

The test A/C system is a copy of that used in the 2005 Chevrolet Suburban with rear A/C. It has an orifice tube on the front evaporator and a thermal expansion valve (TXV) on the rear evaporator, a receiver/dryer and a suction filter in front of the compressor. This is a large system with lots of places where refrigerant can hide from a vacuum pump. However, the total refrigerant charge is 3 pounds (48 ounces), and recovering 95 percent means that up to 2.6 ounces can remain in the system and the machine will still pass the certification test.

WHY ALL THE FUSS?

The first specification standard for R-134a recycling equipment was written in 1988 and deployed in 1991. Although there have been several updates, the basic strategy behind the standard has remained unchanged.

At the urging of SAE and EPA, engineers at General Motors ran several tests of the same equipment used by its dealers by recovering a known refrigerant charge from a 2005 Chevrolet Suburban with rear A/C. After each recovery cycle, the vehicle sat at room temperature for 24 hours, then a second recovery was run on what should have been an empty system. Each second attempt recovered an average of an additional 5.5 ounces (160 grams) of refrigerant, roughly 10 percent of the total charge. Further testing revealed that on smaller systems and at low ambient temperatures, up to one-third of the charge can remain in the system.

When pressure decreases, so does temperature. Reducing system pressure during the recovery process reduces the temperature of the refrigerant and everything it touches. After just a small drop in pressure, the temperature is low enough in some parts of the system to freeze any moisture that might be there. If there's moisture near the expansion device, it can form ice that seals that part of the system, shielding it from vacuum. Refrigerant on the other side of that blockage can remain in a liquid state.

So simply holding a vacuum on the system – even for an extended period of time – may not cause any more liquid to evaporate because of the cold temperatures and because the vacuum may not even be reaching every part of the system. Adding heat to the system helps, which is the reason for warming the engine to normal operating temperature before starting the recovery job, but this is not always possible.

Incomplete recovery leads to overcharging because charge quantity specifications are based on a completely empty system. In addition to reduced cooling efficiency, overcharging can drive high-side pressure dangerously high on hot days, increasing the stress on compressor seals and generating more tailpipe emissions because more power is needed to run the compressor. Excess oil in the system also reduces cooling by coating the heat exchanger tubes, thus reducing their efficiency; the natural tendency is to compensate for this by increasing the refrigerant charge.

With help from the automakers and the A/C equipment manufacturers, SAE learned that most A/C systems are overcharged as a result of existing equipment and service procedures and that the technician is often unaware of the overcharge.

Complete recovery and charge accuracy are fast becoming more critical than ever – not just for the reasons mentioned previously, but also for satisfying the customer. It's obvious that being 2 ounces high affects system performance more in a 2003 Nissan Altima that holds 17 ounces of refrigerant than in a 2003 Ford Excursion with rear A/C that holds 56 ounces. As manufacturers try to reduce the life-time carbon dioxide (CO2) "footprint" of their vehicles, all future models will use less refrigerant, some as little as 10 ounces. In a system that small, charge accuracy of 0.5 ounce equals ±5 percent.

THE REAL GOAL

According to the National Oceanographic and Atmospheric Association (NOAA), 20 percent of all the R-134a in the world is loose in the atmosphere. According to EPA, almost 65 percent of that comes from mobile air conditioners, making the Agency responsible for working on that part of the total.

EPA consulted with the automobile industry, A/C service equipment manufacturers and SAE. The result was the formation in 2004 of the Im proved Mobile Air Conditioning (IMAC) Task Force, which consists of four teams with different responsibilities. The work of Team Four is aimed at reducing R-134a emissions during vehicle service and disposal.

So far its work has resulted in new standards for R&R machines, new standards for leak detectors (J2791) and recommendations for improved hose couplings. In only two years, IMAC in general, and Team Four in particular, have identified several significant improvements that can be made with relatively easy and inexpensive changes.

The ultimate goal of IMAC is to avoid having to replace R-134a with a new refrigerant that would force a complete redesign of the automotive air conditioning system. Improving the A/C system itself will reduce emissions, and new service equipment will help, too.

Over the next few years, look for stricter certification requirements and an increased emphasis on training. These will not just be window dressing, because a reduction of R-134a emissions in the atmosphere must be measured to prove the success of the IMAC program. Along with our own EPA, governments around the world are watching.