The Trainer #42: Tips on finding A/C refrigerant leaks

June 1, 2015

The June 2015 edition of The Trainer looks at the use of ultrasound and CO2 for leak detection, as well as offer you tips on using the more conventional methods more successfully.

Pete Meier

How many of you remember the days of automotive a/c systems that held three or four pounds of refrigerant? Back then, it was considered“acceptable” to lose half an ounce of refrigerant per year from a single leak source. Move the clock forward to modern times, though, and you’ll discover that today’s systems are not quite so forgiving. There are numerous models now that use less than one pound of refrigerant to fully charge their systems. Even small leaks can quickly impact system performance, resulting in your customer’s return to the shop at the tail end of the season after having it repaired (or se we all thought) at the beginning of the season. And in some parts of thecountry, there is no season! The demand for a functional a/c system is yearround.

Recovery/recycling/recharge (RRR) equipment can be used to check for the presence of a system leak, and on vehicles equipped with R1234yf it is a required step. But the machine can’t tell you WHERE the leak is. To find the exact location, many of us prefer the use of a refrigerant “sniffer” – a device that detects the presence of refrigerant in the air around the a/ccomponents (if a leak is present).

At least, that’s the idea. Older sniffers would trigger on just about anything and a few years back, the SAE issued improved standardsthat helped quite a bit. But if your shop is like any of the ones I’ve worked in during my career, other factors (like the breeze kicked up by shop fans on a hot summer day) limited the effectiveness of this method when hunting elusive leaks.

Dye is another popular method and can be very effective. One of the drawbacks of dye is the amount of time it takes to circulate through the entire system. Another is the danger of overdosing the system – adding dye to one that has already received a few shots of the stuff. A third is being able to see the whole system, especially the evaporator core, a common source ofleaks.

So what do you do to chase down a stubborn, hard to find leak source?

There are alternatives, and in the June 2015 edition of The Trainer we’ll take a look at the use of ultrasound and CO₂for leak detection as well as offer you some tips on using the more conventional methods more successfully.

Watch more videos from The Trainer series.

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