Air conditioners are able to cool the air using chemical coolants called refrigerants, also sometimes referred to as working fluid or freon, although the actual chemical R22 Freon has been gradually phased out over the past decade or so by order of the EPA. Freon and other refrigerant chemicals are vital for the continued function of the air conditioner unit, so if some freon starts to leak, you’re bound to have trouble with your unit. Luckily, these leaks can be fixed if they’re caught early, and the lost freon can be replaced. Here’s everything you might need to know about freon leaks, how to spot them, and how the problem can be fixed.
What is Freon?
Freon is a refrigerant, a type of non-combustible chemical compound that can exist in both liquid and gaseous forms. These compounds are how all modern air conditioners work. You can think of freon as the lifeblood of any air conditioner unit – if the refrigerant stops flowing, then the whole system ceases to function. Rapid condensation and evaporation of freon is the chemical process that creates a cooling effect on the air inside the unit, which is then blown out into the ducts or the room itself by a blower fan.
Air conditioners contain two different metal coils, one called the condenser coil and another called the evaporator coil, as well as another vital part, called a compressor. The condenser coil holds the freon as the compressor works on it, increasing the pressure and forcing the freon molecules to compress together until the gas becomes a liquid that condenses inside the condenser coil. This process also creates a transfer of energy as the freon molecules are forced to release the heat they’ve been holding into the air. The heated air is blown through a vent out of the unit as exhaust, while the now-liquid freon is transferred to the evaporator coil.
The evaporator coil is essentially the complete opposite of the condenser coil. As the liquid freon passes through the expansion valve into the evaporator, the pressure on it is decreased. This allows it to evaporate, changing from a liquid back into a gas. Just as the compression forced the freon to release heat, the evaporation process allows the refrigerant to absorb heat. As heat energy transfers from the metal sides of the evaporator, the whole coil cools down. A fan then blows air across the cold coils, which absorb the heat from the air before it’s blown back into your home.
So what is a freon leak? A freon leak occurs when something causes a hole to form somewhere along the way during this back-and-forth process. Air conditioners are designed to hold a very specific amount of freon at any one time, so when some refrigerant is able to escape, the efficacy of the whole system is affected. Less refrigerant running through the system means a reduction in heat transfer. The condenser coil is less warm, the evaporator coil is less cold, and more heat is left in the air molecules being blown across the coil and released into the air.
For this reason, a freon leak is one of the most important things for you to keep an eye on. If you notice moisture escaping from your air conditioner, the culprit could be a refrigerant leak. Not only is this bad for your air conditioner, but it could also affect the local environment as the soil below is exposed to freon. It’s absolutely vital that you get any potential leaks looked at by a professional as soon as possible.
What Causes a Freon Leak?
“Why does my air conditioner have a leak?” is one of the most common questions any HVAC contractor will get at their job. There are actually a few different problems that can cause moisture to drip from the unit and give the appearance of a leak – ice forming and melting on the coils, for example – but the most serious one is a genuine freon leak. No matter what the cause, it’s important to make sure the problem is handled immediately before more refrigerant is allowed to escape.
We recommend letting your HVAC technician take care of leaks and other major problems, but if you’re thinking of doing some repairs yourself or just want to be more informed, it’s a good idea to know what causes an air conditioner to leak freon. The most common cause of a refrigerant leak is just good old-fashioned wear and tear. Air conditioners are generally built to be pretty tough, but every mechanical system has a few weak points and A/C units are no exception. One potential point of failure is a rubber seal. The valves that allow freon to pass between the coils and into the compressor have rubber seals surrounding them, and those seals can gradually degrade over time until freon starts to leak. While the refrigerant lines and the coils themselves are made of copper and therefore won’t rust, other parts inside the compressor like the assembly joints can rust and give freon the opportunity to escape.
Even though you don’t have to worry about the copper freon lines rusting, it’s still possible for small pinhole leaks to appear. This is most commonly caused by formaldehyde, a naturally occurring chemical used in many household construction pieces like plywood. Formaldehyde isn’t dangerous to people in low concentrations, but if it’s in your air, it can rest on the copper coils and freon lines and oxidize, creating formic acid. This is called formicary corrosion, and it will gradually eat away at the copper until tiny leaks start to appear. Formic acid will also corrode other parts of the system, so if you have pinhole leaks in the refrigerant lines, there’s a good chance that you’re about to have some leaks elsewhere as well. Formicary corrosion is why most manufacturers are making replacement lines and coils with aluminum since it’s less vulnerable to acidic corrosion.
Once you’ve identified the cause of the leak, you should try to have it fixed as soon as you can. An HVAC technician will generally just replace any parts that have corroded or sprung leaks so the air conditioner can keep running, good as new. We tend not to recommend handling these repairs by yourself since they involve removing the refrigerant temporarily from the lines and returning it after. Handling freon and other refrigerants can be tricky and it’s rarely a good idea to try it without training. If you do decide to fix the leak yourself, make sure you don’t spill any freon on your skin or on the ground.
How to Find the Source of the Leak
If you want to fix a freon leak in an air conditioner, the first thing you need to do is learn how to find where the freon leak is coming from. Sometimes you can see the refrigerant dripping from a leaky valve, but it becomes a lot more difficult when you have pinhole leaks and you can’t see the refrigerant escaping. If the refrigerant is leaking in gaseous form instead of liquid, it can also be difficult to spot the leak. If the source of the leak isn’t immediately obvious, you have to find where the freon comes from another way.
The best way to find the source of a freon leak is with an automatic leak detector. This is a tool used by HVAC professionals that can detect the presence of refrigerant gas in the air, usually through an electric current. Because the current has a known baseline, when freon gas enters the instrument and passes through the current, it causes interference. A technician can run this tool along every inch of the line until the current stops and the leak is detected.
If you don’t have an automatic detector, or you haven’t been able to find the source of the leak, you can always go old-school. Before automatic leak detectors were invented, HVAC contractors used to find leaks using the soap bubble method. This method involves carefully covering the line with a thin layer of detection spray or soapy water. When the water covers the leak, the air escaping the line will create a tiny bubble in the soap. Once you’ve spotted the bubble, you’ve also spotted the leak. As you might imagine, this method is a lot less precise, but it still gets the job done if you don’t have other options.
Similarly, you can insert a small amount of fluorescent dye into the refrigerant as it flows through the lines. The dye will escape through the leak with the rest of the freon, then you can spot it by running a UV lamp over the line. However, this process can degrade the performance of your air conditioner over time, so it’s rarely used anymore. There’s no sense in finding a leak if it’s only going to damage the rest of the system.
Once you’ve discovered where it comes out of, the next step is to patch or stop the leak. You can choose to either handle the problem yourself or get in touch with an HVAC professional.
How to Fix the Freon Leak
Finally, all there’s left to learn is how to fix an air conditioner that’s leaking. As a general rule, it’s good to know how to fix a freon leak in your home. Freon is used in other large appliances like refrigerators, and if it’s allowed to escape into your home in larger quantities, it can cause adverse health effects for you and your family. Exposure to freon can cause nausea, dizziness, and shortness of breath, so if you notice these symptoms you might have a freon leak in your air conditioner or refrigerator.
In general, the best way to fix a freon leak is just to replace the leaky part altogether. Freon leaks are most commonly found in the evaporator coil, which will cost between $1,000 and $2,000 to replace, depending on the model of your air conditioner. When replacing parts, it’s a good idea to take the age of the unit into account. If your air conditioner is more than 7 or 8 years old, it might just be time to buy a new unit instead of trying to fix every problem that emerges. The copper freon lines can also be replaced if they have leaks, but this will require you to remove and store the refrigerant somehow while you make the repairs, which might be difficult without an HVAC technician’s tools.
If you just need to keep the air conditioner running for a few more months while you save up for a new one, you can use sealant to temporarily plug up the leaks. Liquid leak sealant can be introduced into the refrigerant lines and will block any holes it finds. However, the presence of sealant will force the compressor to work harder and reduce the efficiency of the air conditioner. Any leaks filled by sealant will eventually open back up as well, although the fix can last for up to a couple of years if the holes are small enough. We’d only recommend using leak sealant if you need to buy yourself a few more months with your air conditioner unit before replacing it.
Fix Your Air Conditioning System with a Call!
If you’d rather have a professional handle a freon leak in your air conditioning system, a call to an HVAC contractor will have the problem solved in only a few days. If you live in the Bay Area and you think your air conditioner has a leak, or you have other HVAC-related problems, Valley Comfort Heating & Air is here for you. We have years of experience in the HVAC industry and we’re more than capable of taking care of any issues your A/C unit or furnace might have. You can contact us through our website here, give us a call at (707) 329-4120, or come visit us in our Sonoma or Napa Valley locations.