What’s the Best Way to Find a Refrigerant Leak?

Well folks that’s just it. There really isn’t one best way to identify a refrigerant leak. Anyone who has been in the industry long enough knows that every single leak is different. The leak could be caused by vibration, joints coming loose, or just corrosion of the unit over time. Regardless of how the leak occurred, you don’t know what you’re getting into until you start troubleshooting and that troubleshooting is where the leak detection methods come in. Think of yourself as a detective but instead of trying to solve a murder your scouring your air conditioner trying to find that troublesome leak. It’ll be fun, I promise!

What Not to Do

Depending on the person a homeowner will act in one of two ways when they realize their AC is no longer working. They will either:

  • A) make a service call right away at ten in the evening in the middle of August. You know those guys…
  • Or, B) they will try to fix the problem themselves even though they have no knowledge on how their unit works.

In this section I will be discussing the latter type of homeowner. Hell, sometimes these guys get far enough along in the process to know that they do have a leak. The problem is that instead of calling for service they decide to go pick up some 410A themselves and top off their unit. What these guys don’t know is that a properly functioning AC is supposed to be one-hundred percent completely sealed. No refrigerant should ever be getting out. It’s an endless cycle of liquid to gas over and over again. If you have refrigerant escaping then there is another problem. By adding more refrigerant to the system the only thing you are doing is kicking the can down the road. One way to put this is to imagine that you checked the oil on your car and noticed that it was low. So, you grab a few quarts and dump them in… only you have the drain plug out and all of the oil you just put in exits right out onto your garage floor. The same thing is happening when you top off your unit with refrigerant only instead of the refrigerant going on your garage floor it is being pushed into the atmosphere.

Instead of going through the headache of this and then having to call a tech a few weeks later let me suggest the following. Find out rather or not there is a leak, identify it’s location, fix it, and THEN refill your unit with refrigerant. This is the proper way to do it and it is the way to ensure that your unit will be up, running, and blowing cold for an extended period of time.

The Three Detection Methods

  1. Electronic Leak Detectors The electronic leak detector, or sniffers, are some of the most widely used leak detection equipment on the market today. I can almost guarantee you that ever tech has one of these in their tool bag. These tools work great for detecting if there is a leak and also where in the general vicinity the leak is coming from. The downside on these is that they can only reach so far and they can only detect on what they can touch. On top of that if you are in an enclosed are where there is one large leak or multiple small leaks you may find that your sniffer is overwhelmed and cannot distinguish between the levels of refrigerant in the air.
  2. Ultraviolet Dyes – This is an interesting way to find leaks especially on a unit that you know has a leak but you can’t quite pin point the exact location. This method works by having the technician adding the dye to the system and mixing it in with the lubricants. When the dye has been instilled in the system the tech then uses a black or blue light scanning the unit looking for signs of the colored dye coming out of the unit.
    1. It is worth mentioning here that the dye method is not recommended by all manufacturers and in fact could damage your compressor if applied to a non-supporting unit.
  3. Soap and Bubbles – Yes, that’s right. Something that simple. The idea behind this method is to coat the area where you suspect the leak is coming from in a soap/water solution and then watch and wait. Most people use a spray bottle to apply the solution. If there is a leak there then you should see bubbles begin to form at the source of the leak.

    Halide Torch Leak Detection
    Halide Torch Leak Detection

There is an old school method of finding leaks that I am not going to include in my list above. The reason being is I do not believe it to be safe, especially with the types of refrigerants that are gaining popularity today such as R-290 Propane.

This method is known as the Halide Torch. (See picture.) The idea here is that the torch’s flame will turn green when exposed to refrigerants containing Chlorine such as R-12 or R-22.  There are two reasons why this method is not used today. The first being the flammability risk, especially if you are in an enclosed area and working on a Propane unit. The second reason is that this detection method only works on CFCs and HCFCs both of which are practically gone from the market. The world is now full of HFCs and HFOs and the torch will not work on these types of refrigerants.

Types of Leaks

There are two types of refrigerant leaks that you will run into. The first is intermittent. An intermittent leak is just that. It is not a constant leak and could be caused by vibrations, temperature changes, and load on your unit. (If it’s a hot day you will have more stress on your AC which may cause more leaks to occur.) While leaks are a pain they are not an emergency and you could end up going a few years with one of these without seeing much drop in performance.

The other type of leak is a continuous leak. These leaks are the ones that you want to get fixed as soon as possible. Most of the time they are a slow but steady burn of your refrigerant. As I have said before your AC unit should be completely sealed to avoid any contamination but there is no perfect system and leaks will occur. (Especially if you add the element of time into the equation.) These are the leaks you want to get fixed right away.

How to Find Your Leak

The first thing to do is to physically inspect the unit and see if there are any obvious signs. If you are lucky some people can actually hear the leak occurring, similar to the sound of a leak in a tire.

If you can’t hear anything then continue with the inspection. Do you see any signs of lubricant or oil on the outside of your unit? If you see this then there is a good chance your leak is right there or is nearby. This would be a good time to try the soap and bubble method to see if you identify the actual source of the leak.

If there is no sign of oil and you cannot hear anything the next thing to do is to check all of the connection points of your unit. These points such as o-rings, seals, and pressure valves are usually where your leaks will occur. You can check these with either an electronic leak detector or with the soap and bubble technique. At this point you could also use the ultraviolet dye if you wished. If there was a leak you could see the colored dye coming out with your black light.

If after all of these checks you are still not having any luck then unfortunately you are going to have go dive in deeper and hope that you get lucky. Before you start going inch by inch I would suggest checking all of the hoses, tubing, and copper piping around your AC with your leak detector. These are all high breakage points, especially the copper piping. Copper is known to corrode and rot over the years and could be a source of your leak.


I said it before but think of finding your refrigerant leak like being a detective. You’re pretty sure there is a leak somewhere around here and now it is up to you to find it. There is no best way to identify where your system is leaking from. Instead it is experience and knowledge. Should you use a dye in this example? Should you use your sniffer to narrow down your search and then apply a soap solution? It goes back to trial and error and knowing what you are dealing with.

I hope that I was able to help you guys out and if you are looking to purchase an electronic leak detector then I recommend visiting my latest article on the Best Leak Detectors on the market today.