Refrigerant leaks have specific, identifiable causes. Understanding how they develop and how to avoid them will reduce callbacks and ensure efficient cooling for your customer. We spoke with Anthony Maynor of RightTek HVAC Training and Rocky Berger II of ARS/Rescue Rooter to get their expert insights.   

Why Refrigerant Leaks Happen and Where They’re Found 

Environmental Wear 

Maynor says that refrigerant leaks are most often found with older systems. When equipment has been in service for five to 10 years, the indoor evaporator coil becomes a weak point. It rusts, and corrosion eats into the copper, creating pinholes that slowly leak refrigerant.  

“Ninety-five percent of the time, when there are leaks in the system, they almost always turn out to be at the indoor coil,” he says. 

Berger shed some light on why this occurs. He explained that indoor evaporator coils suffer from formicary corrosion, a chemical process that’s caused by the interaction of air, moisture, and volatile organic compounds. All homes have VOCs, but newly built houses have a very high concentration of them from building materials like flooring, carpeting, and paint.  

The tightly sealed building envelopes of modern homes prevent VOCs from venting, so they enter the HVACR system, accelerate corrosion in the indoor coil, and cause the pinhole leaks to develop over time.  

“HVAC systems move the air in the home, so any toxic air passes through the coil,” Berger said. 

Poor Installation Practices 

If you have refrigerant leaks in a newer system, the likely cause is improper installation — specifically, improper brazing technique.  

“In general, it leads to poorly formed joints and weak joints that, even if they don’t leak on day one, with temperature change, expansion, contraction, vibration of things, weather, and other factors, eventually turn out to be a leak,” said Maynor. 

Some of the most common brazing mistakes that Maynor and Berger have seen include: 

• Not flowing nitrogen: Running nitrogen through the copper refrigerant lines during brazing prevents oxidation. When contractors skip this step, scaling occurs inside the lines. This scale thickens with the refrigerant oil, clogging critical components. While it won’t necessarily cause leaks, it creates problems with refrigerant flow elsewhere. 

• Not cleaning surfaces: The joint must be completely clean of oil and dirt before brazing. Debris can prevent the brazing material from fully adhering and wicking into the joint. 

• Improper heating: Using enough heat and operating the torch at the correct angle is crucial for a solid joint. If the copper line is not hot enough, the brazing material will harden and not flow properly into the joint.  

Reduce Callbacks: How HVACR Contractors Can Avoid Leaks in the First Place 

Callbacks are a major inconvenience for HVACR contractors. They’re time-consuming and usually unpaid. If you’re installing a system for the first time or replacing major components, you need to follow proper techniques to ensure leaks don’t form. 

Preparation is Key 

Berger emphasized the importance of preparing the copper lines before brazing. Even though the lines look new, you need to clean them thoroughly.  

“Spend the extra minutes to clean all the dirt off it, scrubbing it with a wire brush or some emery cloth — both the joint and the pipe,” he says.  

He recommends using the right torch for brazing, one that can adequately heat the copper. Many techs cover service ports with wet rags while brazing, and while this is effective, it can also steal heat and reduce the quality of the braze. The joint must be hot enough to properly melt the filler metal. Berger mentioned that the industry is moving away from brazing and more toward press fittings to overcome these challenges. 

Always Perform a Dry Nitrogen Leak Test 

The best way to prevent installation errors is to test for leaks anytime you open the system.  

“If more people would take the time to do a good, thorough, standing dry nitrogen pressure check, we would find and catch a whole lot more leaks right on day one and get them before they become a callback or a chronic issue for a customer,” Maynor said.  

In over 23 years as a contractor, he did this test on every installation and rarely had leaks after installation. 

To get the most accurate reading, it’s very important to follow all the manufacturer’s recommendations for the test. With newer A2L refrigerants, you’re normally required to do at least a one-hour long-standing pressure test. Once you’ve determined there are no leaks, you can then start the vacuum pump and evacuate the system. 

Preventing Refrigerant Leaks with Proper Training 

While it may be difficult to prevent leaks from formicary corrosion, leaks caused by installation errors are entirely avoidable. According to Maynor, most of these mistakes are caused by a lack of training and experience.  

“A lot of folks that learn on the job, they’re trained by someone who’s doing the best they can based on their experience, but maybe they were never trained properly. You get into this season of what I call tribal learning, where one guy teaches the next, who teaches the next. If none of them on the front end ever learned the right techniques, then nobody after really learns the right techniques,” he said. 

The Air Conditioning Contractors of America provides resources to help HVACR contractors learn the correct installation techniques required for leak-free systems. Whether you’re interested in private training for your entire company or a self-paced program to expand your own knowledge, there are options available. Enroll in a class today.