Proper Air Conditioner Leak Detection

Air Conditioner Leak Detection

Every summer we see the same types of issues, the most common of which is low refrigerant. Most of our customers ask us to come by and “top them off”. Generally speaking this is a bad idea. Not because it doesn’t work, but because it potentially wastes your money and can be detrimental to the environment. 

Let me explain. The refrigeration circuit within your air conditioner is a closed system. That means if it’s operating correctly refrigerant doesn’t enter or exit the system. Refrigerant isn’t like gasoline in a car that gets used up and has to be refilled. The refrigerant just recirculates. This means that if you are low on refrigerant you have a leak. 

We are always happy to add refrigerant to your HVAC system to get the pressures and temperatures back within the manufacturer’s design specifications, but if we do not resolve the cause of the leak the refrigerant we add to the system will just leak back out, flushing your money down the drain and potentially damaging the environment. 

If we check your system and find that it is low we prefer to find the leak and see if it can be repaired. 

Here’s how that works…

Phase 1: Initial Detection

When we come out on a service call we earmark 30 minutes to diagnosing the cause of your issues, it’s built into the service call fee. If we find that your system is low we do an initial detection as a part of the diagnosis for no extra fee, it’s a part of the service call. 

Our initial leak detection efforts include checking all major failure points that don’t require taking the system apart. We use bubbles and electronic leak detectors to check all the brazed joints, metering device, and service ports. We also do a visual inspection of both the condenser and evaporator coil. These are the easiest to find and easiest to repair.

If we don’t find anything we then recommend that you employ us to move on to phase 2. This is an extra charge above and beyond the service call.

Phase 2: Pressurized Detection

condenser. We leave about 20 psi of refrigerant in the evaporator coil (about 10% of what the system holds). We then pressurize the evaporator coil with nitrogen up to 250 psi. This will trigger any slow leak to activate. Once the evaporator is pressurized we wait and watch the pressures to see if they drop, which would indicate an active leak. We then use electronic leak detection to search the entire coil for the leak. These are harder to find so when we think we have found it we pause for a moment and try again. If the same place triggers the detector we repeat one more time. After it triggers the detector three times then we feel confident we have found the leak. We then continue to search to see if there are any other leaks. 

Continuing to check is the important point. It is very easy when you are in a hot attic to take the first response from the detector as the answer and move on to repair it. The problem with this approach is that there might be more leaks that the tech missed, which makes the repairs that are made meaningless. Other leaks still waste your refrigerant and money.

If we don’t find the leak we move on to phase 3.

Phase 3: Delayed Detection

UV Dye Leak Detection

If we still can’t find the leak with pressurized detection it is either an incredibly slow leak, or it is in a location we can’t get to with electronic detectors. For those circumstances we would then recommend a delayed approach where we inject a UV dye that also has leak stop in it. If it is a micro leak the leak stop may seal the system and resolve the issue. This is a low percentage fix, so we don’t rely on it to be effective, but it is always possible. The real reason we use this product is for the UV dye. We inject the dye into the system, top off the refrigerant, and wait. If the system continues to leak and the system stops cooling again, usually months or years down the road, we can come back with a UV light and the dye that has leaked out will glow in the dark. If there is more than one leak they will all glow.


How we resolve the leak is a tricky question to answer, every coil is different. If it is in good shape we can try to repair by brazing over the leak, sealing the system shut again. If it is old and corroded then brazing will just melt all the metal causing a bigger leak. In those cases we would need to replace the coil. 

Ultimately, each case is different and each solution will be different. In the end, we evaluate your system, your leak, and your circumstance and discuss the possible options with you.

What you need to be wary of is the AC repair company who comes out, tells you the air conditioner is low on freon, and then charges you to fill it up without even addressing the leak. These type of companies are here for your money, not to solve your problems. They know you will be calling them back in a few months or in a year to come back and put more refrigerant in…paying them more money.

At Prestige Air, we’re here for you, and we want to do the best we can to solve your problems and keep you from spending money needlessly.  

Choose Prestige Air to Keep Your HVAC Running Optimally

If you experience problems with your heating and cooling call Prestige Air. Our expert service professionals have the training and experience to keep your HVAC system in tip-top shape all year long. Call (817) 200-7215 to make sure your heating and cooling are ready for the season!

Prestige Air proudly serves Northeast Tarrant County and the Fort Worth, Texas area including Hurst, Euless, Bedford, Colleyville, Grapevine, Southlake, Westlake, Trophy Club, Keller, Watauga, Haltom City, and North Richland Hills.

We look forward to serving you and your household!

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At ​Prestige Air, we’re a team full of passionate heating and air conditioning technicians who care deeply about our clients. We know that issues with your heating and cooling can be a headache and our goal is to get your issues resolved ASAP so you can get back to living your life stress-free.

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