6 Steps to Finding and Fixing Leaky AC Ducts

Gagne technician checking ducts with flashlight.

If your air conditioner runs all day, yet your home still feels stuffy, the problem may not be with the unit itself — it could be hiding in your ductwork. Leaky air ducts allow cool air to escape before it reaches your living spaces, forcing your system to work harder and wasting money on energy bills. The good news is that with a little guidance, you can spot the signs of duct leaks and take action.

Check out these 6 practical steps to help you find and fix leaky AC ducts in your home!

Step 1: Watch for Warning Signs of Duct Leaks

Before grabbing any tools, start by identifying whether you actually have a duct leak. Common red flags include:

Unusually high energy bills
Uneven cooling throughout your home
Rooms that feel hotter than others
Weak airflow coming from vents

If your air conditioner runs constantly but struggles to keep you comfortable, leaky ducts are a strong possibility. Paying attention to these symptoms early can save you from bigger headaches later.

Step 2: Inspect Visible Ductwork

While some sections of ductwork are hidden behind walls and ceilings, you would be surprised how much you can learn just from a quick visual check of the areas you can reach. Take a walk through your attic, crawl space, or basement where ducts are exposed. Look for obvious gaps, disconnected sections, or loose joints. You may even spot cracks, holes, or areas where insulation is missing.

Another giveaway is dust streaks along the duct seams, which happen when air pushes out through tiny leaks.

Step 3: Feel for Escaping Air

Sometimes leaks are too small to see but easy to feel. Turn on your air conditioner and run your hand slowly along the length of accessible ducts. Pay attention to spots where you notice cool air blowing out.

For a more precise test, you can hold a thin strip of tissue paper near suspected areas. If it flutters, you have likely found a leak. This simple technique is especially helpful in tight spaces where a flashlight alone may not reveal the problem.

Step 4: Seal Small Gaps and Cracks

Once you have pinpointed leaks, the next step is sealing them up. Contrary to its name, duct tape is not the best option for this job since it tends to peel away over time.

Instead, use mastic sealant, a thick, paint-like substance, or foil-backed HVAC tape. Both products are designed to handle the temperature changes and airflow demands inside ductwork. Apply sealant generously over cracks and seams, smoothing it out with a brush or your fingers for a long-lasting bond.

Step 5: Add Insulation for Extra Protection

Even after sealing leaks, ducts can lose cool air if they are not properly insulated. Wrapping ducts in fiberglass or reflective insulation helps prevent energy waste and keeps conditioned air at the right temperature as it travels through your home. This step is especially important for ducts running through unconditioned areas such as attics and crawl spaces, where hot Georgia summers can quickly cancel out your AC’s hard work.

Step 6: Call in the Pros for a Complete Solution

While some homeowners can handle minor duct repairs, larger issues are best left to professionals. If your ductwork is extensive, located in hard-to-reach areas, or has multiple leaks, an HVAC technician can perform a full inspection and pressure test to find every weak spot.

Professionals have the tools and expertise to not only seal leaks but also ensure your entire system is balanced for maximum comfort and efficiency. Investing in professional duct repair can extend the life of your HVAC system and reduce your energy bills for years to come.

Drafty Ducts? Get Help From Gagne!

Leaky air ducts may seem like a small problem, but their impact on your comfort and wallet is impossible to ignore. By following these six steps, you can keep cool air where it belongs and make your air conditioner work smarter, not harder.

If you suspect your home has leaky ductwork or want the peace of mind that comes with a professional inspection, trust the experts at Gagne Heating & Air Conditioning. Our team proudly brings reliable, energy-saving solutions to both home and business owners, from ductless mini-split installation to AC repair in Alpharetta, GA, and beyond.

Contact us today to schedule your duct inspection and start enjoying a more comfortable, efficient home! We’re happy to help our neighbors in Cummings, Doraville, Dunwoody, Johns Creek, Alpharetta, Canton, and surrounding regions.