Find the Leak Without the Guesswork
Leaks are sneaky. The system can look “mostly fine” for weeks, then one busy day tips it over. Cooling drops off, pressures look odd, and the customer is watching you like a hawk.
That’s why a clean leak detection workflow matters. Not just to “find the leak”, but to fix it once. A rushed method can miss the real point, or worse, create a false alarm that sends you down the wrong path.
In Australia, the conditions don’t help. Brisbane humidity can make moisture control harder. Sydney coastal air can punish joints and coils over time. Melbourne cold snaps can hide a small leak in winter, then summer load exposes it. The good news is: you don’t need magic gear. You need a repeatable process.
This guide walks through a practical workflow that uses the four main methods techs compare: electronic leak detection, bubble solution, UV dye, and tracer gas pressure testing. You’ll learn where each one shines, where each one fails, and how to combine them so you don’t do the same job twice.
A “leak” reading from an electronic sniffer can be caused by cleaner overspray, oil mist, or even solvent residue. A workflow that confirms the leak stops false call-outs.
Start With the Basics: What You’re Really Looking For
Before you choose a tool, get clear on the goal. You are not chasing “a number”. You’re chasing a physical escape point, or a repeatable sign that the refrigerant is leaving the system.
A good leak check starts with three simple questions. First: is the system currently running, or is it down? Second: is this a fast leak or a slow leak? Third: can you access the likely leak points safely without ripping the whole unit apart?
If it’s a fast leak, you’ll often see clues. Oil staining near a joint. Frosting on a line in a weird spot. A strong performance drop in a short time. If it’s a slow leak, it’s usually cleaner to pressure test and confirm over time, rather than rely on “quick sniff, quick guess”.
Also be honest about access. A bubble test is brilliant on an exposed braze joint. It’s useless inside a packed coil section you can’t reach. UV dye is great when the leak only shows under running conditions, but it can’t help you on a dead system that can’t run.
One more reality check: temperature and airflow can change what you “see”. A tiny leak can look quiet on a cold morning, then show up when the unit is hot and vibrating. A plume can be pushed away by fans, sea breeze, or rooftop gusts. That’s why the best techs don’t rely on one pass. They rely on a method that gives the same answer twice.
It’s also worth separating “loss of charge” from “bad measurement”. A dodgy Schrader core, a missing cap, or a gauge hose that isn’t sealing can mimic a leak story if you’re not careful. A clean workflow starts by making sure your test setup isn’t the thing that’s leaking.
If you’re setting up your leak finding kit from scratch, a good starting point is the core category that covers the main options: leak detection tools for HVAC and refrigeration.
The Workflow Most Techs Trust (And Why It Works)
Here’s the simple workflow that avoids most mistakes. You don’t need to follow it like a robot, but the order is there for a reason.
Step one is inspection and isolation. Look for obvious oil staining, rubbed pipes, loose Schrader cores, and damaged coil sections. Make sure you’re not about to “find” a leak that is really a service valve left cracked or a cap missing.
On this first step, slow down and treat it like a pre-flight check. Look for pipe rub-through where insulation has worn, vibration points near brackets, and corrosion spots on coastal installs. Check the simple stuff that can waste an hour later: caps present, service port cores not loose, valve stems not weeping, and coil fins not smashed around the header area.
Step two is pressure test logic. If the system is down or you can safely isolate the circuit, pressure testing with dry nitrogen is often the cleanest way to confirm a leak exists and narrow the area. This is where tracer gas thinking begins, even if you’re not using a special tracer blend.
A good pressure test is controlled and repeatable. Use the correct regulator, bring pressure up in steps, and give the system time to settle. Temperature changes can shift readings, so you’re looking for a consistent trend, not a panicked reaction to one moment. If the pressure won’t hold, you’ve proven you have a leak and you can move on with confidence.
Step three is pinpointing. This is where you pick the right method for the job. Electronic detectors are fast for scanning. Bubbles are perfect for confirming a suspected point. UV dye is best for intermittent leaks or leaks that only show under operation. Tracer gas methods are best when the leak is tiny, hidden, or hard to find by other means.
When you’re pinpointing, think in zones. Start at the most likely leak points first: service ports, flare joints, braze joints, coil headers, valve bodies, and any spot that sees vibration or corrosion. If you get a hint, don’t jump straight to “that’s it”. Re-check from a second angle, then confirm with a different method where possible.
Step four is confirmation after repair. The job is not finished when you “fixed a joint”. The job is finished when you can confirm it holds, and you’ve controlled contamination so the system does not die later from moisture and debris.
Confirmation is where you protect your reputation. A quick confirm saves you the call-back, saves the customer drama, and stops “it’s still leaking” arguments later. If you pressure tested to prove it was leaking, pressure test again to prove it’s not. If you found it with a sniffer, use bubbles to show the fix on the exact joint. Make the proof easy to understand.
Pick one method to find, and one method to confirm. That simple habit cuts false positives and stops “maybe it’s leaking” arguments on site.
Electronic Leak Detection: Fast Scanning When You Use It Right
Electronic leak detectors are popular because they’re quick. When someone says “sniffer”, this is what they mean. Used properly, they’re great for scanning coils, valves, brazed joints, flare nuts, and service ports.
The biggest strength is speed. You can cover a lot of ground without dismantling half a unit. This matters on cramped installs, rooftop plant, or packed condensers where access is limited.
The biggest weakness is false readings. Electronic sensors can respond to oil mist, cleaning chemicals, solvent residue, and even strong airflow patterns that push refrigerant away from the sensor tip. If you “chase the beep” without thinking, you can end up fixing the wrong point.
So what does “use it right” look like? First, slow down. Move the probe tip slowly around likely leak points. If you move too fast, you can miss a small plume. Second, control airflow where you can. Strong fan air can blow the leak plume away. Third, confirm at least twice from different angles. A real leak tends to repeat. A false alarm often disappears once you clean and re-check.
Start the scan where the plume is likely to collect. Around a coil header, trace the joints and corners where refrigerant and oil can escape and sit. Around service ports, scan the core area and the cap area, because caps matter and cores can weep. Around flare nuts, scan the underside as well as the top, because gravity and oil flow can change where residue sits.
Also think about what the sensor is “smelling”. If you’ve just sprayed coil cleaner or solvent, give the area time and ventilation before you trust a reading. If the site is windy, shield the probe path with your body where safe, or re-check when the fan is off (if it’s safe and appropriate for the job). The goal is a repeatable reading, not a dramatic beep.
Electronic detectors are most effective after a pressure test has confirmed there is a leak, or when the system is running and you have a good reason to suspect a specific zone. If you’re unsure what to keep in the van, start with the range here and pick the detector type that suits your work: electronic leak detectors and leak checking tools.
Bubble Testing: The Best Confirmation Tool On Accessible Joints
Bubble solution is not “old school”. It’s reliable confirmation. If you can access the joint, bubbles give you a visual answer you can show a customer or a supervisor.
Bubble testing shines on service ports, Schrader cores, flare nuts, braze joints, valve stems, and accessible fittings. It is also brilliant after you’ve repaired something, because you can confirm the fix without arguing about sensor drift or sensitivity.
The weakness is access and patience. If you can’t reach the joint, you can’t bubble it. If the leak is extremely small and airflow is strong, bubbles can take time to form. That’s why bubbles are often the “confirm” step, not the “scan everything” step.
A good bubble test is clean and controlled. Wipe the area first so you’re not bubbling over dirt and oil. Apply enough solution to cover the joint. Then watch. Don’t rush it. On tiny leaks, the bubble growth can be slow but obvious if you give it a moment.
One practical tip is to bubble under stable conditions. If your test pressure is jumping around because valves are being adjusted or gas is still equalising, you can confuse yourself. Let it settle, then bubble. On service ports, don’t ignore the cap. A good cap helps seal, and a bad cap can be part of the story when a system slowly loses charge.
If you want a straightforward, tradie-friendly option to keep on hand, this is a common pick for confirmation work: bubble leak detection solution for HVAC joints and service ports.
UV Dye: Best For Intermittent Leaks And “It Only Leaks Sometimes” Jobs
UV dye is a different tool for a different problem. It’s not meant to replace pressure testing or bubbling on a visible leak. UV dye is best when the leak is intermittent, hard to access, or only shows under real running conditions.
Think about the job where the unit holds for weeks, then drops charge again. Or the leak that only happens when the coil warms and cools. Or the leak hidden inside a cabinet where you can’t get a probe tip close enough to trust it.
The workflow with dye is simple in concept. The dye circulates with the refrigerant and oil. When it escapes at a leak point, it leaves a visible trace that lights up under UV. That trace can guide you straight to the problem area, even if the leak is too small to show bubbles quickly.
The key is control. Dye should be used thoughtfully, not as a first guess. You also want to keep it clean. Avoid spilling dye in the unit, because that creates a mess and makes future checks confusing. The other key is patience. You often need run time to give the dye a chance to circulate and show itself.
UV work is also about visibility. In bright daylight, a faint trace can be easy to miss. If you’re checking an outdoor unit in full sun, shade the area where you can and take your time. On refrigeration cabinets and plant rooms, lighting and access can be tight, so having the UV gear ready and easy to deploy matters more than people think.
If you’re looking for dye and the supporting bits, start here and choose what matches your workflow: UV dye and accessories for HVAC leak detection.
Tracer Gas And Pressure Testing: The Clean Way To Prove A Leak Exists
When the system is down, or when you want a clean proof that a circuit is leaking, pressure testing is usually the first serious step. Most techs use dry nitrogen for this, because it’s inert and it doesn’t add moisture when done properly.
Pressure testing does two things well. First, it tells you if the circuit holds or not. Second, it narrows the search. If you can isolate sections, you can work out whether the leak is in the indoor coil, outdoor coil, line set, or valve area.
Tracer gas leak detection is the next layer. Some workflows use nitrogen only. Others use a tracer blend designed for sniffing. The key idea is the same: you put a clean test gas in, then use a suitable detector method to find the escape point.
Here’s the practical reality. On many everyday HVAC jobs, nitrogen pressure testing plus good scanning and bubbles is enough. Tracer blends become more useful when the leak is very small, very hidden, or the site conditions make normal scanning unreliable.
Whatever method you use, do not cut corners with safety. Use the correct regulator. Use the correct rated hoses. Never use oxygen for pressure testing. And follow manufacturer guidance for test pressures, because the right pressure depends on the equipment and the refrigerant class.
Pressure testing also rewards patience. If you’re dealing with a tiny leak, a short test can lie to you. A longer hold, under stable temperature conditions, tells the truth more often. If ambient temperature changes fast, readings can drift even when the system is tight, so you’re watching for a pattern that makes sense, not a single moment that triggers panic.
A solid regulator setup makes pressure testing safer and more controlled. This is the kind of gear that fits that role: nitrogen pressure regulator for HVAC pressure testing and leak checks.
Pressure testing should be done with dry nitrogen and the correct rated gear. Test pressure varies by system. Follow the unit documentation and use controlled steps so you don’t damage coils or valves.
Method Comparison Table: Electronic vs Bubble vs UV vs Tracer Gas
People often ask, “Which method is best?” The honest answer is: it depends on the leak and the access. The table below keeps it practical so you can pick the right tool for the job in front of you.
| Method | Best for | Where it struggles | How to confirm | Gear you’ll typically need |
|---|---|---|---|---|
| Electronic leak detection | Fast scanning of joints, coils, valves, and service ports | False positives from chemicals, airflow blowing plume away, very windy areas | Repeat the check from different angles, then bubble the suspected point | Electronic detector, good access, patience and slow probe movement |
| Bubble solution | Confirming an exposed leak point with a visual result | Hidden leaks, tight coil sections, leaks that only show under operation | Watch for steady bubble growth at pressure, then re-check after repair | Bubble solution, clean rag, lighting, stable test pressure |
| UV dye | Intermittent leaks, hard-to-reach leaks, repeat mystery leaks | Dead systems that can’t run, messy installs, poorly controlled injection | Find dye trace under UV, then confirm repair with pressure test or bubble check | Dye and UV accessories, clean injection process, time for circulation |
| Tracer gas and pressure test | Proving a leak exists, isolating sections, tiny leaks on dead systems | Requires isolation and correct gear, not ideal if you can’t access test points | Hold test over time, then pinpoint with electronic scan and bubble confirmation | Nitrogen regulator, rated hoses, gauges/manifold, safe work practice |
Contamination Control: The Bit That Saves Compressors
Leak detection is not only about finding the leak. It’s also about not contaminating the system while you do it. Moisture and dirt are the silent killers. They don’t always fail the unit today. They shorten its life and create the “why did this compressor die early?” problem.
Contamination control starts with your gear. Keep hoses capped when not in use. Don’t drag hose ends across floors and throw them straight on a service port. If you’re pressure testing, keep the nitrogen setup clean and dry. If you’re using dye, keep it controlled and avoid spill contamination in the cabinet.
It also includes what you do after the repair. If you’ve opened the circuit, you need a proper evacuation. That’s not “nice”. That’s how you remove moisture and non-condensables that create future headaches and acid formation.
On real jobs, contamination control is a chain. One weak link can undo the good work. A hose end left uncapped in a humid van. A fitting that has dirt in the threads. A leaking manifold valve that slowly pulls air back in. The system might still run today, but it’s the kind of setup that creates odd behaviour weeks later.
It’s also why confirmation matters. If you prove the system holds after repair and you keep your handling clean, you reduce the odds of repeat leaks and “mystery faults” caused by moisture and non-condensables. You’re not just finding a hole. You’re protecting the whole system lifecycle.
If you’re checking your hose kit and fittings, a good starting point is a dedicated category where you can pick hoses that match your day-to-day work: HVAC hoses and couplings for service, testing and charging.
If you’re pressure testing, you’ll also want the right rated setup and a clean process. That’s where the regulator and hose combo matters more than people think. It reduces accidental over-pressure, reduces messy venting mistakes, and makes your test repeatable.
Rig Setup: Make Your Leak Checks Faster (Without Cutting Corners)
Rig setup is about being consistent. When your kit is set up the same way every time, you work faster and make fewer mistakes.
For electronic scanning, keep the detector ready and protected. Store it where the sensor won’t get smashed. Keep spare batteries or charging habits consistent. Clean the tip area if you’ve been around solvents or heavy oil mist.
For bubble checks, keep your solution and rag accessible. Don’t bury it under five tool bags. You want to be able to confirm a suspected leak point on the spot, not after a trip back to the ute.
For UV dye work, keep the UV gear together. Dye, light, glasses, and cleaning wipes in the same kit. UV work fails when you can’t find the light or you can’t see the trace clearly.
For pressure testing, keep the regulator, hoses, and gauges matched. Don’t use random hoses that are not rated for the job. And don’t pressure test with gear that leaks at the fittings, because you’ll end up “finding a leak” in your own setup.
Consistency also helps with training. If your team runs one standard setup, you reduce the “who moved the adapter?” chaos and you get more reliable results across different techs. When you know exactly how your rig behaves, you spot a real leak faster because your baseline is stable.
If you’re building out your measurement and diagnostic kit, this is the kind of category that usually holds the tools techs use every week, including manifolds and related test gear: HVAC test and measurement gear including digital manifolds.
Purge And Venting: Do It Clean, Do It Legal
Leak detection often sits right next to refrigerant handling work. That means your process has to be safe and compliant. It also has to protect the system.
Purge thinking is simple. When you connect and disconnect, you want to avoid pulling air into the system and avoid pushing contamination into the circuit. If you’re recovering, charging, or opening a circuit for repair, use proper recovery and evacuation practices and don’t take shortcuts that leave moisture behind.
Even on “quick checks”, keep your habits consistent. A sloppy connect-and-disconnect can drag air into a line, and you don’t always feel the pain immediately. The damage shows up later as unstable operation, odd pressures, and repeat failures that waste your time. Clean habits are boring, but they’re what separate a tidy workflow from a messy one.
In Australia, refrigerant handling is linked to licensing and safe practice. If you need the official reference point for that side of the job, use this one: ARCtick refrigerant handling licensing in Australia.
On the equipment side, a proper evacuation process is a big part of contamination control after a leak repair. If you’re doing any work that opens the system, you want a reliable vacuum pump and a way to prove the vacuum is stable.
For evacuation gear that suits Australian trade work, these are the categories most techs start with: vacuum pumps for HVAC evacuation after leak repair and micron gauges to confirm a stable evacuation.
Common Mistakes That Waste Hours
Most leak detection problems come from the same few habits. Fix the habits and the job gets easier.
The first mistake is skipping the “prove it” step. If you don’t confirm the circuit is leaking, you can spend an hour scanning a unit that is actually low for a different reason, or that has a service valve issue, or that has a measurement error. Pressure test logic keeps you honest.
The second mistake is moving too fast with an electronic detector. Fast scanning feels productive, but it misses small leak plumes. Slow, repeatable movement wins more often than high speed.
The third mistake is believing one reading. A workflow should confirm. Electronic scan points you to the zone. Bubble confirms the joint. Pressure test confirms the system holds. UV confirms intermittent leaks. Each tool has a job.
The fourth mistake is ignoring contamination. You can fix the leak and still create a future failure if you leave moisture and debris in the system. That’s why proper evacuation and clean handling are part of a leak workflow, not a “nice extra”.
The fifth mistake is not thinking about environment. Coastal air can corrode coils and joints over time. High humidity can add moisture risk if evacuation is rushed. Tight installs can cause heat stress and vibration that turns a small leak into a repeat leak. Your leak fix should consider the cause, not just the hole.
Another common trap is chasing the rare leak first instead of the common leak. Service ports, flare joints, and valve stems cause a lot of real-world headaches, especially on units that have been serviced a few times. A tidy workflow checks those early, confirms with bubbles where possible, and only then starts pulling panels off and diving deep.
And finally, don’t forget your own gear can be the problem. A leaking hose gasket, a damaged core tool, or a regulator fitting that seeps can create “ghost leaks” that waste time. If your readings don’t make sense, swap to a known-good hose or fitting and re-check before you blame the system.
Choosing The Right Method For The Job In Front Of You
So, what should you actually do on Monday morning when you get a leak call?
If the system is down and you can isolate the circuit, start with pressure testing logic and prove the leak. Then use electronic scanning to narrow the zone. Then use bubble solution to confirm the point you plan to repair.
If the system is running and the leak is suspected but not proven, start with inspection and sensible electronic scanning around the usual suspects. If you get a repeatable reading, confirm it with bubbles where possible. If it is not accessible, consider whether dye makes sense for that job.
If the system is a repeat mystery leak, UV dye can be a smart move, especially when the leak is intermittent and only appears under certain load or temperature conditions. Keep the dye process clean, run it long enough to show itself, then confirm the repair after the fix.
If the leak is tiny and hidden, or if you have repeated “no leak found” results, bring pressure testing and tracer gas thinking back into the workflow. Tiny leaks often need time, isolation, and methodical scanning to show up cleanly.
On residential split systems, leaks often show up at flare joints, service ports, and coil headers. On these jobs, electronic scanning plus bubbles can be a strong combo because access is usually reasonable if panels come off cleanly. On refrigeration cabinets, access and airflow can be trickier, so slow scanning and patience matter more, and dye can become useful when the leak only shows under operating conditions.
On rooftop and windy sites, plan for airflow. A plume can be blown away fast, so you may need to re-check from multiple angles and confirm with bubbles wherever you can reach. If you can’t reach the likely points and the system is down, a clean pressure test that isolates sections is often the fastest way to stop guessing.
Next Step: Build A Simple Leak Detection Kit That Matches Your Work
A leak workflow is only as good as the kit you can actually use on site. You don’t need every tool under the sun. You need the right mix for your jobs.
A practical base kit usually includes an electronic detector for scanning, a bubble solution for confirmation, and the gear to pressure test safely when the job requires it. UV dye is a smart add-on if you do repeat commercial work or you regularly see intermittent leaks.
Think about your most common call-outs. If you’re mostly doing service and fault finding, scanning speed and confirmation are your bread and butter. If you’re doing installs, compressor swaps, or major repairs, pressure testing gear becomes more important because you’re opening circuits and you need clean proof before you charge and commission.
If you’re refreshing your setup, start with the main leak detection category and choose what matches your work type: leak detectors and leak detection accessories. For pressure testing and cleaner rig setup, pair that with a reliable regulator and rated hoses so your test results are trustworthy: nitrogen regulator for pressure testing and leak checks and service hoses and couplings for HVAC work.
If you want a low-pressure next step, talk to our team and describe the type of work you do. Is it residential splits? Light commercial? Refrigeration cabinets? Let us know if you mostly see fast leaks or slow leaks, and whether you need scanning speed or confirmation strength. We’ll help you match a leak detection workflow and a kit that makes sense, so you spend less time guessing and more time finishing jobs cleanly.