What Causes Refrigerant Leaks in Air Conditioners

What Causes Refrigerant Leaks in Air Conditioners

    If your air conditioning system leaks refrigerant, it can lead to major problems such as lower energy efficiency, higher bills, and a shorter lifespan for your HVAC system.

    We’re here to guide homeowners in identifying refrigerant leaks, pinpointing the root causes, and discovering how to fix them. Our ultimate goal at Watkins Heating & Cooling is to keep your AC running optimally and ensure a cool and comfortable home environment.

    The Myth of An Air Conditioner Using Up Freon

    Many homeowners think that, over time, an air conditioner uses refrigerant. The thought is that a long, hot summer can leave a perfectly good air conditioner “winded” and low on refrigerant. Many customers think, “We just need to tune up the A/C and top up the coolant, right?” However, the reality is that air conditioning units and heat pumps do not consume Freon. Refrigerant is not fuel, so the AC is not consuming it, and in theory, it is not something that should ever have to be charged or changed. The refrigerant system in an air conditioner or heat pump is a sealed loop that should never “use up” or run out of refrigerant. The only resource that is expended is electricity.

    So, if the refrigerant is not consumed in the process of cooling your home, how is it lost?

    Refrigerant leak in copper coil. Tube wall under magnification
    Leaking copper coil tube wall after corrosion test

    What Can Cause an Evaporator Coil to Leak?

    In our experience, if there is a Freon leak in your air conditioner, 9 times out of 10, the leak will be located in the copper tubing of your evaporator coil. The location is nearly always in plate-fin copper tubing, which is made paper thin for maximum thermal efficiency. Indoor coils also leak more frequently than outdoor coils because the average indoor space is chalked full of pollutants. In fact, studies by the EPA have found indoor air to be approximately 2 to 5 times more polluted than outdoor air on average.

    This leads to the primary cause of refrigerant leaks…

    Formic Acid Corrosion Causes Freon leaks

    Formicary Corrosion happens when the contaminants in your home’s air mix with water on the indoor coil to create formic acid, a mild acid that attacks copper. Over the course of several years, this acid bores microscopic holes into the copper tubing creating tiny pinhole leaks. We call them champagne leaks because if you were to plunge the evaporator coil into a water tank, you would see hundreds of very fine bubbles.

    Engineers at Trane, one of the leading air conditioning manufacturers, were some of the first identify this as the culprit behind coil refrigerant leaks. They discovered that formaldehyde in homes was turning into formic acid on the evaporator coils, gradually corroding pinhole leaks in the copper tubes over several years. Formaldehyde, a significant indoor air pollutant, has been infamous for its high concentration in situations like the FEMA trailers for Katrina victims. But even in the air inside the average American home, there are detectable levels of formaldehyde, leading to the inevitable AC Freon leak.

    For years, the air conditioning industry has favored evaporator coils made of copper because of the metal’s ductility and excellent heat transfer, but studies like Trane’s proved that copper was particularly vulnerable to formicary corrosion. To make matters worse, the industry started using thinner copper tubes to help meet the Department of Energy’s increased standards. This meant that the acid corrosion can penetrate newer model indoor coils much faster. After trying various coatings with little effect, the industry has finally adopted all-aluminum indoor coils, which is drastically reducing leaks.

    Trane aluminum coil tube wall under magnification
    Trane aluminum coil without leaks after corrosion test

    Everyday Wear and Tear

    Another cause of ac refrigerant leaks, particularly with an older AC unit, is attributed to the natural aging process. Over several years of use, every HVAC system undergoes varying degrees of natural wear and tear, including weakened connections and deteriorated rubber seals around valves and fittings. Regular tune-ups certainly help detect these issues and fix them before they become a bigger problem. AC units over 15 years old will all have some level of aging, and sometimes, this can lead to a coolant leak.

    Mechanical Vibrations

    There are a few different elements that could cause excessive mechanical vibrations in your air conditioning unit, and occasionally, our HVAC technicians see this lead to leaking refrigerant. Some contractors take shortcuts including soldering connection rather than brazing. Soldered joints, whether plumbing solder or silver solder, do not stand up well to vibrations.

    It’s also common for two copper lines to cross inside an AC unit. Over time, normal vibration from the compressor will cause the lines to rub on each other, eventually creating a large hole. Manufacturers protect against this by securing the tubing and using rubber isolators. Over the years, these can decay and lead to big issues.

    Physical Damage

    Generally, when we see physical damage it’s to the condenser coil. The condenser coil’s outdoor location makes it susceptible to environmental factors like severe weather and even dogs who like to hike a leg and pee on the unit, leading to rapid corrosion of the aluminum. Our technicians have also seen the outdoor unit hit with weed whackers and run over by riding mowers and student drivers. We’ve even seen the neighbor’s kid shoot a condenser coil with a pellet gun!

    One potential way to prevent physical damage is to have your AC unit installed on the wall elevated off the ground or to have some fencing around the unit.

    Factory Defects

    With today’s quality controls it’s rare, but sometimes air conditioners leave the factory with a defect. If the unit loses its Freon charge shortly after installation, the cause may be a factory defect. Corrosion and vibration take several years to impact the air conditioner. A problem in the first year is likely either a faulty braze joint by the installation team or a weak joint made in the factory.

    Assembly joints inside the air conditioner are made in a factory by a combination of robots and humans. If the robot is calibrated wrong or the human had a bad day, the connection may fail shortly after install. Trane sets itself apart with some of the most thorough testing in the air conditioning industry. Multiple quality checks during their process make it exceptionally rare for any Trane coil to have a defective joint from the factory.

    Improper Cooling System Installation

    The HVAC installer also brazes the field joints on-site at your home. A faulty field joint is easy to find and fix since the connections are out in the open. Our install process including a thorough test with high-pressure nitrogen followed by a deep vacuum confirmed by a micron gauge. Any problems with the field joints become very obvious with this two-step quality control process.

    It’s important to note that low refrigerant levels don’t always mean a leak. We often receive calls at Watkins Heating & Cooling from customers with low Freon who had their HVAC system installed by other companies. When our team finds low coolant levels in these air conditioning systems, it’s often because the initial HVAC installer did not set the coolant levels correctly. The A/C isn’t low because it leaked; it was low from the very start.

    Air conditioners come preloaded with a standard refrigerant charge at manufacturing, typically around 5 or 6 pounds. This factory charge is only enough for very short linesets, and the air conditioner should be fine-tuned after installation. Standard practice for many of our competitors is simply to release the charge and then leave without taking the time to complete a proper commissioning.

    At Watkins, we take an extra hour after installation to make fine-tuned adjustments. Our technicians use digital gauges to dial in the perfect pressures and “sub-cool” so that the efficiency and capacity meet the manufacturer’s specifications.

    Research shows that being off by as little as 10% in refrigerant level can lead to a 10-20% drop in energy efficiency! The scary part is that the units in the study were still cooling just fine. They were simply using more electricity than necessary. So, while you might have purchased a new AC unit with a high SEER rating of 15, poor installation and startup could effectively reduce its efficiency to a performance equal to that of a 12 SEER unit! This means that you’re not getting the efficiency you paid for and it will cost you in the long run.

    HVAC aluminum coil to copper coil comparison
    HVAC aluminum coil and copper coil corrosion comparison

    Signs of an AC Refrigerant Leak

    Now that you know the root causes leading to AC refrigerant leaks, let’s explore some of the signs you might notice if your cooling system is not at its best.

    Lack of Air Conditioning System Airflow

    This is the most obvious sign of a refrigerant leak that you’re likely to notice: when your air conditioner is running, but it’s not blowing cool air. If your air conditioning system is turned on, but the air coming out of the vents is not cool, we often find that the air conditioner is low on coolant. All the components of the A/C can be operating properly, but, without the correct Freon levels, the A/C cannot cool your home. If this is something you’re dealing with right now, your first step is to get an expert diagnosis so you know exactly what’s causing the issue and your options to fix it.

    Air Conditioning Unit Freeze-Up

    Another common sign of a coolant leak is a frozen evaporator coil. It may sound counterintuitive, but when your Freon levels are low, it can actually cause your coils to become excessively cold and ice up. When the Freon levels are correct (about 125 PSI for R-410A refrigerant), the indoor coil temperature gets down to about 40 degrees Fahrenheit. This cool temperature condenses tons of moisture from your air, efficiently removing humidity while cooling your home. If the air conditioner refrigerant levels drop and the pressure falls below 100 PSI, the coil’s temperature will drop below 32 degrees, and the humidity that condenses on the coil will quickly freeze. You’re most likely to notice the ice forming around the insulated tubing coming out of the cooling unit. Sometimes the first sign may be water puddling on the floor because the drain pan is blocked by ice.

    Note that while a frozen coil often indicates low Freon levels and a possible leak, a clogged air filter or bad indoor fan motor can also cause similar freezing. To determine which you may be dealing with, we recommend turning off the cooling system to thaw, changing the filter, and restarting to see if the issue persists.

    Increase in Indoor Humidity

    As we explain here, the refrigerant works in your AC system to cool your home AND remove humidity. So, when there isn’t enough refrigerant… the humidity will be higher! Moisture levels will rise and you might feel the air in your home gradually become heavier and stickier, making hot days feel even hotter. This is an early warning sign of a coolant leak, so get your A/C checked out right away.

    Spike in Energy Bills

    If your air conditioner has a refrigerant leak, you’ll feel the effects is significantly higher energy bills. You may think that just putting some more Freon into the system will fix your energy bills, but a top-off is only temporary unless you fix the problem. While it may cool for several months, it will only maintain peak efficiency for a few days after it’s recharged. Unless the leak is repaired, the refrigerant level is already dropping, and your efficiency will be getting worse every day.

    If you’re getting a recharge, make sure the technician does a full leak search to find the root problem and get your A/C working correctly. While the repair may be expensive, sometimes it can be an easy fix.  No one wants to waste electricity, let alone have their precious new coolant leak out right away.

    Hopefully we’ve helped you gain a clearer understanding of the causes and symptoms of a refrigerant leak. If you’ve noticed one of the signs above, you should take action right away before Freon leaks cause more damage to your air conditioner. To see estimated costs to repair refrigerant leaks, check out our page on AC repair pricing. A no-hassle service call is the surest way to know the real problem with your air conditioner and we always have friendly, professional techs on standby. Give us a call or simply fill out the form below to book a service appointment!

    Contact Us

    • Please let us know any other information about your request
    David Watkins

    David Watkins

    As a third generation HVAC professional, David Watkins grew up around all things heating and air conditioning. He is an expert in airflow and duct design and he leverages his math and science background to lead an HVAC team well-known for their technical capabilities.

    Other Recent Blog Posts

    Trane XV20i Humidity Thermostat Setting
    Uncategorized

    Ideal Indoor Humidity Levels and the Benefits of Optimum Humidity

    We all want a home that feels just right – a space that’s comfortable, cozy, and welcoming. Achieving the ideal indoor humidity level is ...
    Read More
    HVAC Worker Brazing Copper Coil
    HVAC Replacement

    Nitrogen Brazing vs Soldering for Refrigerant Lines

    Your home's HVAC system is a complex network of components working to keep you comfortable. At the heart of this system is something most ...
    Read More
    HVAC Brands and Parent Companies Infographic
    HVAC Replacement

    Overview of Furnace and Air Conditioner Brands: An HVAC Company Family Tree

    Most HVAC brands are part of larger parent companies. To make sense of the HVAC industry, it’s helpful to understand how various air conditioner ...
    Read More
    Watkins HVAC Technician Cleaning Air Conditioner Coil
    Service and Repair

    Air Conditioner Coil Cleaning: Improve Efficiency & Save Money

    Keeping your air conditioner running smoothly and efficiently doesn’t have to be complicated, but it does require staying on top of regular maintenance. One ...
    Read More
    Heat Pump Unit Covered in Ice
    Service and Repair

    Heat Pump Defrost Cycle: Understanding the Process and Trane’s Innovative Approach

    Heat pumps are just like air conditioners except they have a "reverse gear." By changing direction of the refrigerant flow, they can not only ...
    Read More
    Air Conditioner Tax Credit Rebate
    Watkins News

    What HVAC System Qualifies for Tax Credit 2024?

    Homeowners in Ohio have a fantastic opportunity to save money on new HVAC systems with federal tax credits available throughout 2024. If you're considering ...
    Read More
    Air Conditioner vs Heat Pump
    HVAC Replacement

    Heat Pump vs Air Conditioner: Which HVAC System is Right for You?

    The Difference Between a Heat Pump and Air Conditioner When it comes to heating and cooling your home, understanding the difference between a heat ...
    Read More
    Trane XV20i and Trane XV18 Air Conditioner
    HVAC Replacement

    Difference Between Trane XV20i and XV18 Heat Pump and Air Conditioner

    When looking for the best A/C or heat pump for your forever home, the Trane XV20i and XV18 models stand out as the top ...
    Read More
    Trane HVAC Heat Pump Indoor Outdoor Unit Combo
    HVAC Replacement

    Heat Pump A/C Combo Setups: Cool Summers, Warm Winters

    Choosing a new heating and cooling system can be confusing with all the different options for heat pumps, air conditioners, furnaces, and air handlers. ...
    Read More
    Furnace Carbon Monoxide Cause Inspection
    Indoor Air Quality

    What Causes Carbon Monoxide in Homes

    Understanding Carbon Monoxide Carbon monoxide (CO) is a colorless, odorless, tasteless gas that can be deadly in your home. It is often referred to ...
    Read More
    Woman with CO Poisoning Symptoms Headache
    Indoor Air Quality

    Recognizing the Signs and Symptoms of Carbon Monoxide Poisoning

    What is Carbon Monoxide? Carbon monoxide gas (CO) is a deadly, invisible threat. Because carbon monoxide is a colorless, odorless, and tasteless gas, it ...
    Read More
    Watkins Trane 2023 SOAR Award for Dayton Cincinnati
    Watkins News

    Watkins Heating and Cooling Wins the 2023 – 2024 Trane SOAR Award

    We're thrilled to announce that Watkins has been honored with this year's prestigious Trane SOAR Award for the Dayton and Cincinnati, Ohio area. This ...
    Read More
    Air Conditioning Lightning Strike
    Service and Repair

    Understanding Air Conditioner Lightning Strikes

    If you live in the Miami Valley, you’re more than familiar with the regular spring and summer thunderstorms! They can be pleasant to fall ...
    Read More
    Loveserves board visiting a pastor in Guatemala City
    Missions and Ministry

    LoveServes Guatemala 2024

    Last week, my wife and I visited the beautiful country of Guatemala to visit Saq B'e, one of our LoveServes partners. Our purpose was ...
    Read More
    APCO UV Light Installation in HVAC System
    Indoor Air Quality

    How to Prevent A/C Evaporator Coil From Leaking Freon

    Refrigerant, commonly referred to as Freon, is essential to the functioning of your air conditioning system. Your air conditioner pumps refrigerant around, absorbs heat ...
    Read More
    Watkins HVAC Tech Check AC with Leak Detector
    Service and Repair

    What Causes Refrigerant Leaks in Air Conditioners

    If your air conditioning system leaks refrigerant, it can lead to major problems such as lower energy efficiency, higher bills, and a shorter lifespan ...
    Read More
    Watkins HVAC technician checking AC refrigerant Freon levels
    Service and Repair

    What Refrigerant is Used in Home A/C Units?

    Refrigerant is the lifeblood of your home’s air conditioning system. It circulates between your A/C's indoor evaporator coil and the outdoor condenser coil, transferring ...
    Read More
    Cutaway view of Trane heat pump air conditioner showing spine fin condenser coil
    HVAC Replacement

    Trane Aluminum Spine Fin Coils – Pros and Cons

    Trane All-Aluminum Spine Fin™ Coils The Trane Spine Fin™ condenser coil is a distinctive and patented technology used by Trane in their air conditioning ...
    Read More
    Watkins HVAC tech stands with new Trane XV20i heat pump after replacement job
    HVAC Replacement

    Can I Replace Just My Air Conditioner Without Replacing My Furnace?

    Can I Replace the AC Unit Without Replacing the Furnace? It's one of the most common questions we get in the HVAC world and ...
    Read More
    SEER2 EnergyGuide Air Conditioner Rating Label
    HVAC Replacement

    What the New SEER2 Standards Mean for Air Conditioners and Heat Pumps In 2024

    What is SEER? What on Earth is SEER2, how is it different than the regular old SEER rating, and what does it mean for ...
    Read More
    Watkins Gas Furnace Cleaning Maintenance
    HVAC Replacement

    Cracked Heat Exchangers

    Scam alert! Each heating season, numerous Dayton heating contractors are tempted to lie about cracked heat exchangers in an attempt to sell more furnaces. ...
    Read More
    Danfoss thermal expansion valve TXV
    Service and Repair

    Understanding the TXV

    The HVAC TXV (Thermal Expansion Valve). How it works and why it fails. When it comes to a heating & cooling system, there are ...
    Read More
    Watkins AC Repair Man
    Indoor Air Quality

    Top 10 Most Common HVAC Issues and How to Prevent Them

    A well-functioning HVAC system is essential for maintaining a comfortable and healthy living environment in your home. However, HVAC systems are complex and can ...
    Read More
    Replace install hvac heat pump air conditioner
    HVAC Replacement

    Discovering Heat Pumps: Your Guide to Energy-Efficient Home Comfort

    Switching to a heat pump in Ohio's climate Heat pumps are becoming increasingly popular as an energy-efficient and environmentally friendly heating and cooling solution ...
    Read More
    Trane Air Conditioner WeatherGuard Cover
    Service and Repair

    Air Conditioner Covers

    Protective Covers for Air Conditioners: Do You Really Need Them? Autumn's arrival often raises concerns about outdoor air conditioning units. Falling leaves, snow, and ...
    Read More
    Rafa and John building a wall
    Missions and Ministry

    Teaching, Building, and Changing Lives in the Dominican Republic

    We just got back from another great mission trip to the Dominican Republic. Over the past few years, we have been working with a ...
    Read More
    Home Heating and Cooling Rebates
    HVAC Replacement

    Utility Heating & Cooling Rebates Explained

    In the Miami Valley there are three utility companies offering rebates. The purpose of the rebates is to drive higher efficiency across the region ...
    Read More
    AC Manufacturing Warehouse
    HVAC Replacement

    Factory Warranties

    For last few years, the heating industry has waged a “warranty war” with the various furnace brands offering longer and longer parts warranties. We ...
    Read More
    Watkins Employee Does Maintenance on HVAC System
    Indoor Air Quality

    Home Humidity 101

    We are only halfway through December and we've already installed a full winter's budget of Aprilaire humidifiers. It looks like static and dryness have ...
    Read More
    Watkins Heating and Cooling help St. Vincent
    Missions and Ministry

    Introduction to Our Work in St. Vincent

    Randy and I left chilly Ohio on January 4th for a three-month missions trip to the island of St. Vincent. Our son-in-law, Daniel, attended ...
    Read More
    Air Conditioner Leaking Water on Floor
    Service and Repair

    Air conditioner maintenance | Water leaks

    I have been a service technician with Watkins Heating & Cooling for over 10 years now. Every spring I have a routine to prepare ...
    Read More
    solar powered hvac company
    Watkins News

    Zoning for Solar Energy

    When it comes to zoning laws, perception is nine tenths of the law (how's that for a mixed metaphor)? You may own your home, ...
    Read More
    Watkinsheating Hiring !
    Watkins News

    We’re Hiring!

    The huge referrals from our wonderful customers have us a little overwhelmed. We need to add more seasoned service and installation techs to our ...
    Read More
    Mitsubishi Zoned Comfort ductless mini-split heat pump
    HVAC Replacement

    It Is Cold Upstairs! Comfort Tips for a Two-Story Home.

    I live in a two-story house built in the sixties. Like many homes in the Miami Valley, temperatures can vary widely from upstairs to ...
    Read More
    Watkins Tech Explaining New Trane Air Conditioner XR16 Install to Customer
    Service and Repair

    REAL Service Technicians

    I believe I can speak for most service technicians when I say we all love to talk shop. If you were to listen in ...
    Read More
    Dominican Missions
    Missions and Ministry

    Watkins’ Mission to Transform Lives in the Dominican Republic

    For years our family has been personally involved in overseas missions work. Our business is seasonal which makes it easy to get away in ...
    Read More
    Technician working on a high efficiency furnace
    Service and Repair

    Top 5 Reasons for a Furnace Tune-up

    Homeowners frequently ask, “Why does my furnace need a tune-up every year?” As our techs will tell you, a neglected furnace will eventually leave ...
    Read More
    Best HVAC Repair Google Search in Tab
    Service and Repair

    How Do You choose an HVAC Contractor?

    Baby it's warm inside! It is 6:30 PM, and you have just returned home from a grueling day at work. You are ready to ...
    Read More
    heat pump thermal balance point
    HVAC Replacement

    Heat pump operation 102

    In my last post, Heat Pump Operation 101, I explained how the efficiency and capacity of a heat pump vary with the weather. How ...
    Read More
    Watkins Service Technician Heat Pump Maintenance Tune-Up
    HVAC Replacement

    Heat pump operation 101

    Many homes in the Miami Valley are heated and cooled by Heat Pumps, but few homeowners understand how they work. Hopefully I can dispel ...
    Read More
    Honeywell Carbon Monoxide Alarm
    Service and Repair

    Carbon Monoxide Safety

    With the time-change, local news stations always recommend changing the batteries in your smoke detector. Furnace guys would extend that reminder to carbon monoxide ...
    Read More
    furnace_filters
    Indoor Air Quality

    6 Furnace Air Filter Tips

    A question asked quite often by my customers is, “How often should I change my furnace filter?” Another popular question is, “Why do you ...
    Read More
    gas pilot light before and after cleaning
    Service and Repair

    Routine furnace maintenance saves money

    I’m sitting here in my two-seat, diesel powered office thinking about the season. There are reminders everywhere; trees without leaves, frost covered grass, Christmas ...
    Read More
    Trane ECM motor module
    Service and Repair

    Committed to Your Comfort: Trane Heat Pump Repairs Done Right

    This morning, we encountered a malfunctioning ECM fan control module on an older Trane heat pump. These modules are crucial for your unit’s performance, ...
    Read More
    Hope House Rescue Mission Dayton Logo
    Missions and Ministry

    Watkins Brings Comfort through Hope House Rescue Mission

    Reprint of press release from PRWeb. Watkins Heating and Cooling today announced a two-year commitment to provide free furnace and air conditioner maintenance to ...
    Read More
    Heating Check
    Service and Repair

    Goodbye Freon!

    I am sitting in a class today getting some continuing education for my Ohio master license. Today’s course is a review on R-410a (Puron), ...
    Read More