How to Fix a Refrigerant Leak in Your AC Unit

What Causes an AC Unit to Leak Refrigerant?

An AC unit leaks refrigerant primarily due to corrosion on the copper coils, physical damage to the refrigerant lines, or poor installation of the HVAC system. Over time, volatile organic compounds (VOCs) in your home's air can cause formicary corrosion, creating microscopic pinholes in the copper tubing.

Understanding the root cause is the first step toward a permanent solution. Your home AC unit is a closed-loop system, meaning it does not consume refrigerant like a car consumes gas. If the refrigerant level is low, a leak is absolutely present.

Common causes of HVAC refrigerant leaks include:

• Formicary Corrosion: Chemical reactions between the copper coils and household chemicals (like hairspray, cleaning supplies, and air fresheners) create tiny holes.
• Vibrations: Constant operational vibrations can cause copper lines to rub against other components, wearing them down until a leak forms.
• Weak Joints and Connections: Poor soldering during the initial installation can degrade over time, leading to slow leaks.
• Physical Damage: Yard work, falling debris, or accidental impact to the outdoor condenser unit can damage the lines.

David Clendennen, owner of Clendennen Service in Marble Falls, Texas, explains some of the common causes of refrigerant leaks in air conditioning systems.

“There are a lot of different causes for leaking,” Clendennen said. “The coil itself may develop a leak due to something from the manufacturing process, or over time it can develop small pinholes for various reasons.

“I’ve also seen cases where a dirty filter causes the unit to freeze up, and that freezing process can worsen an existing weak spot in the coil or even contribute to a leak. In other situations, physical damage can be the cause, such as when outdoor equipment is struck by debris or a rock while mowing the yard.”

How Can You Tell If Your HVAC System Has a Refrigerant Leak?

You can tell your HVAC system has a refrigerant leak if your home takes longer than usual to cool down, the air coming from the vents is warm, or ice begins to form on the evaporator coils.

Here are the most prominent indicators that you need to fix a refrigerant leak in your AC unit:

1. Loss of Cooling Power: The most obvious sign is a decline in your system's cooling capacity. The AC will run constantly but fail to reach the set temperature on your thermostat.
2. Hissing or Bubbling Sounds: A large leak in the refrigerant line may produce an audible hissing sound, while a leak in a submerged section might cause a bubbling noise.
3. Frozen Evaporator Coils: When refrigerant levels drop, the evaporator coil cannot absorb heat effectively. This causes the condensation on the coil to freeze, leading to a block of ice inside your indoor unit.
4. Spike in Energy Bills: As the HVAC system works harder and runs longer to compensate for the lost refrigerant, your monthly electricity usage will skyrocket.
5. High Indoor Humidity: Refrigerant helps remove humidity from the air. A leak will leave your home feeling sticky, warm, and uncomfortable.

Why Should You Fix a Refrigerant Leak Immediately?

You should fix a refrigerant leak immediately to prevent total compressor failure, stop environmental damage caused by escaping greenhouse gases, and restore your home's energy efficiency.

How to Fix a Refrigerant Leak in an AC Unit

To fix a refrigerant leak in an AC unit, professionals follow a strict protocol: detect the exact location of the leak, recover all existing refrigerant, weld or patch the damaged copper lines, pressure test the system with nitrogen, and recharge the AC unit with fresh refrigerant.

Here is the step-by-step breakdown of how your local Carrier dealer will restore your system to peak performance.

Step 1: Detect the Leak Source

A technician detects the leak source using an electronic refrigerant leak detector, UV dye, or a specialized soap bubble solution applied to the copper lines and joints. The electronic detector sniffs out chemical traces in the air, while the UV dye and bubbles provide visual confirmation of the exact pinhole or crack. This precision ensures that no secondary leaks are left behind.

Step 2: Recover Remaining Refrigerant

Before any repairs can take place, the technician must recover the remaining refrigerant using a specialized recovery machine and a certified recovery tank. Venting refrigerant into the air is illegal and harmful to the planet. By safely extracting the remaining chemicals, the technician ensures a safe workspace and protects the environment.

Step 3: Repair the Leaking Component

To repair the leaking component, the technician will either cut out the damaged section of copper tubing and braze (weld) a new piece in its place, or replace the entire evaporator or condenser coil if the corrosion is extensive. Brazing requires high heat and precision to ensure a completely airtight seal that can withstand the high operating pressures of a modern HVAC system.

Step 4: Test the HVAC System for Leaks

After the repair, the technician tests the HVAC system for leaks by pressurizing the lines with oxygen-free dry nitrogen. The system sits under high pressure for a designated period while the technician monitors the pressure gauges. If the pressure holds steady, the AC repair is successful. The nitrogen is then released, and a vacuum pump is used to remove all air and moisture from the lines.

Step 5: Recharge the System with Refrigerant

Finally, the technician recharges the system with the exact amount of refrigerant specified by the manufacturer. They will weigh the refrigerant as it enters the system and monitor the system's superheat and subcooling temperatures to ensure the HVAC unit operates at maximum efficiency.

Can You Fix an AC Refrigerant Leak Yourself?

No, you cannot fix an AC refrigerant leak yourself because handling HVAC refrigerants requires EPA Section 608 certification, specialized recovery equipment, and high-temperature brazing tools. Attempting a DIY repair is illegal, dangerous, and will likely void your equipment warranty. Always trust your local Carrier dealer to handle home cooling repairs to ensure safety and compliance.