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.
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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.