If you’ve ever found yourself sweating in your living room while the thermostat insists it’s 71 degrees, you’re not imagining things. The problem often isn’t your air conditioner—it’s your humidity level, and one of the biggest contributors to high indoor humidity is duct leakage.

New Jersey’s Humidity Creates the Perfect Storm

New Jersey summers are known for high humidity. It’s not uncommon for outdoor humidity levels to exceed 70-80%, creating that heavy, sticky feeling we all know too well.

Think about it this way:

A 90-degree day in humid New Jersey feels much hotter than a 90-degree day in dry Las Vegas. The temperature may be identical, but the moisture in the air makes a dramatic difference in comfort.

The same thing happens inside your home. Your thermostat may say 71°F, but if your indoor humidity is elevated, your home can feel closer to 78-80°F.

How Duct Leakage Causes Humidity Problems

According to the U.S. Department of Energy, the average home loses 20-40% of conditioned air through duct leakage. While most homeowners think of duct leaks as simply wasting energy, they can also become a major source of heat and humidity infiltration.

Many homes have ductwork running through unconditioned spaces such as:

• Attics
• Crawl spaces
• Garages
• Wall cavities

During the summer, New Jersey attics can easily reach 120-140°F, with humidity levels often significantly higher than the conditioned air inside your home. When ductwork develops leaks, two things happen:

Leaks on the Return Side

Return ducts are designed to pull air from inside your home back to the HVAC system. However, when return ducts leak in a hot attic, they begin pulling in attic air instead. This means your air conditioner may be trying to cool and dehumidify air that is:

• 120-140°F
• Loaded with moisture
• Filled with attic dust and contaminants

Instead of conditioning 75°F indoor air, your HVAC system is now fighting against attic conditions.

Leaks on the Supply Side

Supply duct leaks allow conditioned air to escape into the attic. As cooled air leaks out, the home becomes negatively pressurized, often causing additional hot, humid outside air to infiltrate through gaps around doors, windows, recessed lights, attic penetrations, and other building leaks. The result is even more humidity entering the living space.

Why Your AC Can’t Keep Up

Your evaporator coil is responsible for removing both heat and moisture from the air. When duct leakage continuously introduces hot, humid attic air into the system, the coil becomes overwhelmed.

Instead of spending all of its capacity cooling your home, it’s forced to first remove the additional heat and moisture being sucked in through the leaks.

As a result:

• Humidity remains elevated
• Cooling performance decreases
• Energy bills increase
• Equipment runs longer
• Comfort suffers

The thermostat eventually reaches 71°F, but the moisture remains.

Comfort Is More Than Temperature

Most thermostats only measure temperature. They do not measure how comfortable the air feels.

A home at 71°F and 65% humidity can feel significantly warmer than a home at 75°F and 45% humidity because high humidity prevents your body’s natural cooling process through evaporation. That’s why many homeowners keep lowering the thermostat but never seem comfortable.

The Real Solution: Address the Duct Leakage

If your home feels humid, sticky, or uncomfortable despite the AC running constantly, duct leakage should be investigated.

Sealing duct leaks can:

• Reduce humidity infiltration
• Improve comfort
• Lower utility bills
• Improve airflow
• Reduce HVAC run times
• Increase equipment lifespan
• Improve indoor air quality

Technologies such as duct leakage testing and Aeroseal duct sealing can identify and seal hidden leaks throughout the duct system, helping your HVAC system control both temperature and humidity as it was designed to do.

The Bottom Line

If your thermostat says 71° but your home still feels hot, don’t automatically blame the air conditioner. In many New Jersey homes, the real culprit is duct leakage pulling hot, humid attic air into the HVAC system.

When attic temperatures reach 140°F and humidity levels soar, even small duct leaks can have a major impact on comfort, efficiency, and indoor air quality.

Fixing the leaks doesn’t just save energy—it helps your home feel the temperature your thermostat says it is.

At Advanced Air Duct Cleaning, we provide duct inspections, duct leakage testing, Aeroseal duct sealing, and indoor air quality assessments to help homeowners eliminate hidden comfort issues caused by leaky ductwork. Contact us today!