Jun 23 2020

Motor car service #Motor #car #service

Motor car service

By Paul Weissler

April 2019 Issue

You’ve no doubt heard about the phase-in of R-1234yf. The changeover from R-134a is far from complete, but it’s definitely gaining momentum, with plenty of new equipment built to suit.

The changeover to R-1234yf is still not complete, but more than 20 million cars and light-duty trucks on U.S. roads are already equipped with the new refrigerant, and most new models’ air conditioning systems are being filled with it. You can’t just tab R-1234yf as “unlikely to see” anymore. The earliest systems, primarily in some Cadillacs and the Jeep Cherokee, are six years old, and due to some collision work and just some normal a/c service work may have already been showing up for repair. Because so few independent repair shops are equipped to handle vehicles with R-1234yf, the business is going primarily to dealerships.

A study by Neutronics, maker of refrigerant identifiers, revealed cases in which dealer markups for customer-pay work was not just substantial but could be argued as excessive. The reason is that dealers presently have little or no competition from independent shops. But the opportunities are there and will only be increasing because the majority of 2018 and later vehicles have R-1234yf.

Are the new systems more prone to problems? No. In fact they’re tighter (much better sealing, including the compressor shaft seal) and should be more robust, as the evaporators must pass a salt spray test for corrosion. However, the new systems have been engineered to require much smaller refrigerant capacities, resulting from a push for greater system efficiency and the fact that the new refrigerant is ten to 20 times the price of R-134a. So just a few of what hitherto would have been considered small leaks can create a loss of performance, because the typical system has perhaps a 10% margin in refrigerant capacity; 10% of an 18-oz. system means just about 2 oz. lost is the limit.

Domestic nameplates commonly install trace dye wafers on the assembly line. They dissolve and circulate with refrigerant oil as soon as the system is put into operation. Import nameplates (including those made in the U.S., Toyota/Lexus being the notable exception) approve trace dye as a service aid, even if they don’t install it in production. It’s a good idea to sell a regular customer on a dye injection when the vehicle is in for any regular service, so down the road, when the inevitable leak does occur, you may see a dye trace. The simple truth is that today’s systems keep most of the oil in the compressor; as little as less than 10% may circulate. Time is its friend, and it can easily take a week or more of a/c operation for a leak to show up.

With R-1234yf currently wholesale-priced at $660 to $750 and up for a 10-lb. jug (with the price likely to increase as the a/c season gets underway), a customer will not be enthusiastic about paying a retail price of perhaps $200 to charge an empty system. Then he has to tolerate letting it leak out so you have a chance of finding the leak. And then he has to pay again for a recharge (plus labor to fix the leak). That’s why a premium electronic leak detector—one that meets SAE J2791 and/or J2913—gives you your best shot at finding a leak with just a few ounces of refrigerant in the system. Although they’re more expensive, our best results have come with infrared detectors. Furthermore, the SAE J2843 standard for R-1234yf includes a gross leak test procedure that specifies a J2913 detector.

The easiest leak to find and fix is one at the service valves. It’s also typically the most common leak because so many vehicles do not have the primary seal on—the valve cap. One reason is that it’s sometimes simply misplaced after removal for a pressure check, or it slips from the fingers of the technician who’s removing it and rolls out of sight.

Does it fall to the ground? Chances of that happening are somewhere between rare and none. Little parts that fall from at or near the top of an engine compartment go into crevices and stay there. You can look with a flashlight and rock the vehicle up and down and the result usually is the same—no luck. When that happens, if the shop doesn’t have a spare cap that fits, the car goes out the door without one.

If it happens early in the day, a conscientious shop often will add the cap to the parts order from the jobber. But sometimes the cap is out of stock. In fact, when we tried to find a jobber that carried valve caps for R-1234yf systems, we couldn’t find a single one. Just as bad, none of the dealers in the area had any either, and when they checked their nearest warehouse, they came up empty there, too.


USA News. American News.

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