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MACS 2019 Mobile A/C update

Wednesday, May 1, 2019 - 06:00
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And while it would also rescind the self-sealing valves, we don’t expect to see them go away. Can makers spent huge sums of money changing over their production lines to manufacture self-sealing cans, and market prices have already adjusted to the change. Plus, the adapters and hose sets are readily available, and getting rid of them now would seem to be unfavorable.

So, at the time of this writing (March 2019), we don't know exactly what's going to happen. All we’ve heard from EPA so far is that they’re planning to announce their next regulation soon (maybe before this year’s A/C season starts), so we’ll just have to wait and see.

Aftermarket modifications of MVAC systems

Sometimes after a vehicle is manufactured by an OE, it’s sent to an outfitter for modification. These can range from luxurious interiors (including rear seat beverage coolers and secondary A/C systems) in limousines, party buses or conversion vans, to converting a vehicle for accessible use. When the technician needs to modify the factory A/C system to do this, they are required to comply with EPA’s SNAP use conditions for the OE refrigerant.

This basically means that if a vehicle was originally manufactured with an A/C system that uses R-1234yf, then the technician needs to keep that system, any additional A/C circuits, and any additional refrigeration loops, as still using yf and not some other refrigerant or blend. This also applies to R-134a vehicles.

Figure 1 - Bus A/C installation varies depending on its configuration. On left is “Type A” made from an incomplete chassis. On right is a “Type D” transit style converted to look like a trolley train car. Note its skirt-mounted condensing unit, just forward of the rear axle

But as you’ve no doubt seen before, not too many of these modified systems are set up exactly the same from one vehicle to another. See Figure 1. That’s just how it is with custom mods. EPA knows this, and from the feedback they’ve received from installers, they provided some guidance for the industry as to what would be acceptable to the regulator.

For example, if a technician is adding rear A/C to an extended van with an existing front / dash mounted system, they are required to use the same refrigerant as the OE. So, if it’s an R-134a system, you must keep it R-134a. Likewise if it’s an R-1234yf system, you must use yf in the conversion, while also following the SNAP use conditions for yf (like using an evaporator that meets SAE Standard J2842).

In another scenario, some modifications require the installation of a second (or even a third), completely separate A/C system. An example would be installing A/C in a school bus or party bus, which are sometimes so big, and have so much interior space that has to be cooled, that even with two evaporators, one compressor just can’t do the job, and so a second compressor with one or two more evaporators is required (Figure 2). Because these buses usually start out as incomplete chassis by the OE, they are not allowed to use yf refrigerant, and R-134a needs to be used in each of the separate systems. However, if it’s a modified complete chassis which originally came with yf, any additional refrigeration loops (including second or third compressors) must be filled with yf and not R-134a.

Figure 2 - This bus actually has three compressors, but only the top two can be seen. The OE is mounted low on the passenger side, while these two add-ons are right up top. Each powers an independent loop, with the three systems using different amounts of R-134a refrigerant.

Primarily the reason is because EPA does not want vehicles running around with two A/C systems that use two different refrigerants, as this presents an all-too-easy opportunity for refrigerant cross-contamination. But they’re also concerned with technicians trying to defeat safeguards (like using service port adapters that convert a system from a low-GWP refrigerant to a higher one).

MACS 2018 field survey

Every few years MACS conducts a survey of both our member shops and non-member shops to find out how A/C service is being performed and what are the most common issues facing technicians today. We ask questions about how many services are performed in a given week, how many of each A/C component are replaced, and even how many problems could not be solved. We had great participation this year, and here’s just a bit of what we learned.

Figure 3 - (Courtesy of Ward Atkinson) Survey respondents serviced 2,073 R-134a systems, which accounted for 26 to 50 repairs being done per week during the 2018 summer season

Shops on average are servicing between 26 and 50 A/C systems during the peak season, and as you would expect, most of the customer complaints are simply, “It ain’t coolin’.” The majority use R-134a, but we’re seeing more yf systems in the aftermarket (more than 200 shops reported working with yf) as some of these vehicles have now been out of warranty for two or more years. See Figure 3.

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