Are you ready for the HVAC service challenges coming to your shop?

May 1, 2018
Refrigerant levels aren’t the only specification that is dropping. Lubricating oil specs are also on the decline, with several models using less than two ounces.

Back in 2005, I participated in a national contest looking for the “A/C Technician of the Year,” hosted jointly by the Mobile Air Conditioning Society and Carquest Technical Institute. It was a wonderful experience, with the semi-finalists invited to the headquarters of Hendrick Motorsports for the last leg of the competition. There, we were challenged first with a 100-question written exam and then with a series of practical work stations that challenged our repair and diagnostic abilities. It was the first year of the event and I’m proud to say that I was the overall winner that year. 

A lot has changed over the last 12 years and the knowledge that took me to the winner’s podium then is only somewhat applicable now. Are you up to date with all the new technologies and processes you’ll need to continue to successfully service these systems? 

The fundamentals have changed 
I was around when R12 was the norm and charging a vehicle’s A/C system was simple. Using a manifold gauge set and a scale, we would charge the system to specification and then add or subtract a bit to get the best pressure readings and coldest air out of the ducts. And that process was fine, considering that systems of the day held two or more pounds of refrigerant.

Replacing an evaporator is a routine procedure, but if replacing one used in an R1234yf system be sure to use a new one that meets the SAE standard.

But that is not an acceptable process today, yet I read of techs who are still using this archaic method. Why is this method no longer acceptable?  

System capacities are dropping with many late-model platforms equipped with less than a pound of refrigerant. Overcharging by as little as 10 percent can cause compressor head temperatures to rise, leading to premature failure of the compressor itself. Undercharging by the same variance will certainly impact the system’s ability to provide the comfort the occupants deserve.  And if you’re confident you’re ok using that old RRR (Recovery/Recycling/Recharging) machine you’ve had for years, you may want to think again. Unless it’s certified to at least the SAE J-2788 standard, it isn’t accurate enough for these cars either.  

And while we’re talking about refrigerants, have you tried to buy any lately? You may have run into a rude surprise when the man behind the counter asked to see your EPA Section 609 card! As we tried to tell you, the EPA changed the rules effective January 1 of this year. It is now required not only for the purchase of R12 (when was the last time you bought any of that?), but any MVAC refrigerant in containers over two pounds in size. And yes, the DIYers can still buy the little cans from the Big Box stores all day long. And no, I don’t get it either.

It’s required to perform a refrigerant analysis on R1234yf systems before the machine will let you recover the charge. It’s good practice to perform an analysis on ANY car you intend to connect to your service equipment.

Refrigerant levels aren’t the only specification that is dropping. Lubricating oil specs are also on the decline, with several models using less than two ounces. That is vitally important for a few reasons. One, there is little room for error when adjusting the oil level while making a repair to any component in the system. On most of these cars, the oil stays in the compressor rather than flow through the system but there is still a trace amount in the evaporator, condenser and other components. It is critical that you review the OEM’s oil balancing procedures to insure that you don’t over- or under-fill the system. As a side note, be sure to rotate the new compressor through several times prior to start up to avoid accidentally causing a hydraulic lock when it engages. This isn’t due to the oil in the compressor, but the refrigerant that collects there when the vehicle sits. Two, the use of dye additives to inspect for leaks must be carefully monitored. It, too, can result in overfill issues if randomly added to the vehicle. And because the primary oil charge stays in the compressor, the dye will take a while to circulate through the system. You’ll have to inform your customer that they’ll have to drive the vehicle around for a while before returning to your shop for inspection. 

(Image courtesy of Robinair) System charge capacities are getting lower every year. Only a machine certified to SAE J-2788 or higher is qualified to recover and recharge these systems.

R1234yf 
Like it or not, R1234yf is here to stay. Currently, there are nearly 41 million cars around the world equipped with the R134a replacement. The first domestic OE to use R1234yf on a U.S. production car was GM, with two Cadillac models in the 2012 MY. FCA (Jeep, Chrysler, Dodge and Fiat) was the first domestic manufacturer to employ R1234yf on a wide scale, starting in the 2014 MY. Keep in mind that, at the time, R134a was still the “go to” gas in the States but OEMs were able to earn carbon credits if they switched over to a more “environmentally friendly” refrigerant. That becomes important to us in a moment, so hang in there with me. 

Consider that now, most of these vehicles are out of factory warranty and heading for your shop for service. Are you prepared to deal with them? 

In order to service R1234yf systems, you’ll need an SAE J-2843 RRR machine, an SAE J-2912 or J-2927 refrigerant analyzer, and an SAE J-2913 leak detector.  These tools are mandatory to comply with the EPA law. A few companies are offering machines capable of servicing both R134a and R1234yf, so if you haven’t upgraded in a while, that may be a better option for you.  

Let’s take a closer look at some of these needs. I’ve found listings on E-Bay offering to sell you a new J-2788 R134a machine that has been “refitted” to service R1234yf. Do NOT – I repeat, do NOT try to take this shortcut. All they are doing is buying manifold line adaptors and fitting them to the lines. But R1234yf is considered “mildly flammable” and machines built to the standards include components to limit the possibility of igniting the gas. Using a machine that is not so equipped could put you and your employees at risk, both physically and financially. Like Sheriff Justice said in the original “Smokey and the Bandit,” “You can think about it – but don’t do it!” 

You know what the orange cable means, right? HV compressors require a special oil to avoid HV leakage that could result in a vehicle shutdown.

Another requirement for servicing R1234yf is the need to perform a refrigerant analysis on the serviced vehicle before the machine will allow you to recover the vehicle’s charge. The identifier can be built into the unit, or attached separately using a USB connection. The reasons for this are obvious. R1234yf is not cheap, with a 10-pound container retailing for $1,000 in my area. This is a gas you are not going to want to waste and certainly, you don’t want to contaminate it with something that’s not supposed to be there.  

The (expected) reality 
First, let’s squelch this rumor right now. Yes, the EPA has regulated a “phase down” of R134a in the United States but R134a isn’t going anywhere for a long time to come. We will not be retrofitting any R134a cars to R1234yf, like the fiasco we went through with R12. However, I think we’ll see a lot of the opposite. DIYers for sure, and perhaps even some shops, will be using R134a in R1234yf systems. There are more than a few problems with that idea, though. At the top of the list is the fact that it’s illegal. Since most OEMs earn emissions credits for using R1234yf systems, installing R134a in its place is “emissions tampering” and that carries a hefty $25,000.00 fine (per occurrence)! It is also in violation of EPA regulations regarding “acceptable use”. Either could put a shop that gets caught out of business. 

And you can bet that DIYers that own cars equipped with R1234yf that are out of warranty are going to sign on to Google the first day their system doesn’t cool as it should. Their favorite YouTube “expert” will show them how to top off their cars with R134a, a procedure that hasn’t been “acceptable” for years on ANY modern A/C system. Or they’ll just blow whatever gas is left in the system to the outside air and refill the whole thing with R134a. Either way, the charge is contaminated and you can’t recover it with your R1234yf machine and you certainly don’t want to contaminate the tank in your R134a cabinet. 

Remember that old R134a machine you have in the corner? That may now be your “junk” machine, used to collect whatever soup you find in your customers’ systems. Just make sure you use the right tank and dispose of the mix properly. 

(Image courtesy Toyota Motor Co.) The 2017 Prius Prime uses a “vapor injected” heat pump to keep occupants warm on those cold winter days. It also changes your diagnostic flow when faced with a “low heat” complaint.

Here’s another DIYer nightmare you need to be aware of. You’ll find YouTube videos that were made by “professionals” showing users how to use “Dustoff,” that aerosol you use to clean off your computer keyboard (and containing the SNAP-approved refrigerant R152a, a flammable gas) to charge their cars. That’s a potential safety hazard to your techs! What do you do then? Sorry, Charlie, take that one down the road! 

Let’s not forget the hybrids 
While you’re shopping for that new machine, be sure you are aware of the needs of your hybrid and EV customers, what few there may be. Any vehicle using an electric compressor requires a different type of lubricating oil, one that is not conductive, or you may find yourself on a road call to retrieve a car that won’t start.  

But that’s old news and we’ve covered that extensively in past issues of Motor Age.

(Image courtesy of Nissan) When used to cool the cabin, the Leaf’s refrigerant circuit is pretty normal with the exception of a few new components.
(Image courtesy of Nissan) When heat is needed, the valves isolate the evaporator core and primary orifice tube from the circuit, instead forcing the pressure change to occur on the low side of the refrigerant path.

What we haven’t talked about are potential new service opportunities for your shop on the heating side of HVAC. In 2013, Nissan introduced the first automotive heat pump system on their full electric model, the Leaf. In 2017, Toyota introduced a modified version, called a “vapor injected” heat pump system, on the Prius Prime. The introduction of this technology to production cars may very well spike an interest by other automakers looking for any means to increase the EV range of their offerings. Toyota, for example, claims a 20% increase in range on the Prius Prime. These systems operate similarly to the heat pumps used to heat our homes but it does change the diagnostic flowcharts when it comes to troubleshooting a “low heat” complaint! 

Basically, a heat pump is just an A/C system running backwards. Instead of releasing heat to the outside air at the condenser, the condenser is used like an evaporator to draw heat into the refrigerant for later release in the passenger cabin. When you first look at the refrigerant circuit on the Leaf, you’ll find a fairly normal system when used for cooling. The only additions are an additional heat exchanger, two special valves and a second orifice tube. 

Google R134a to R1234yf adaptors and you’ll be amazed at the results. These are designed to convert an R134a manifold gauge set to R1234yf fittings. There are even fittings that allow a direct connection between an R1234yf service fitting to an R134a hose.

When heat is requested, the two valves are used to redirect refrigerant flow. One, the three-way valve (see accompanying illustration), redirects flow in order to bypass the orifice tube and evaporator. The other, a two-way valve, is closed to force refrigerant through the second orifice tube, called the Heating Orifice Tube.  

Let’s follow it around to fully understand how the system functions, starting at the point of pressure change. High pressure liquid refrigerant leaves the cabin’s Inner Condenser and passes through the Heating Orifice Tube, where it drops pressure and of course, temperature. This allows the refrigerant to enter the condenser as a low pressure vapor (small droplets of refrigerant) at a temperature lower than the outside air temperature (OAT). Since heat travels to cold, the hotter outside air loads up into the refrigerant where the conversion to a low pressure gas takes place. 

This heat-laden low pressure gas now enters the compressor and leaves as a high pressure gas, further raising the temperature of the refrigerant. It then enters the Inner Condenser where the heat is transferred to the cabin by the circulation of the blower motor across the heat exchanger. The loss of heat begins the process of returning the refrigerant to a liquid state on its way back to the orifice tube. 

In the case of the Leaf, if the OAT is too low for the heat pump alone, there is a supplemental PTC (Positive Temperature Coefficient) heater to back it up. 

The system on the Prius Prime is similar with one important difference. Included in the system is a liquid-gas separator and a small injection pump. The injection pump is used to inject vaporized refrigerant in the compressor during the compression cycle. This is called an “economizer” and takes advantage of the Vorhees Principle to increase the efficiency of the heat pump. Toyota claims that the heat pump system is effective to 14[Symbol]F. If you live in an area where it gets colder than that, don’t worry. The conventional heater core is still present as is a supplemental PTC heater.  

Yes, the HVAC systems in play today have come a long way since that 2005 contest. Like other vehicle systems, they are featuring high technology and require service processes that have less room for error. As I asked at the start – are you ready?

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