condensation on ac ventExcessive moisture can cause homeowners a lot of problems: corrosion, rotted drywall, warped wood, and blistered or peeling paint. It can even attract insects, damage sensitive electronics, and lead to mold. Moisture’s bad no matter where it is, but condensation on AC vents is especially harmful because, instead of remaining confined to a single room, its effects are felt throughout the entire house. In extreme cases, vents “sweat” and drip water down the wall or onto the floor.

Condensation forms when hot, humid air comes into contact with a cold surface. If the surface temperature is below the dew point, the water vapor in the air condenses and becomes liquid. No doubt you’ve seen the same thing happen hundreds of times. Leave a cold glass out on a hot day and eventually a layer of water appears on its surface. Condensation appears on your AC vents for the same reason, though, owing to the complexity of your cooling system, it can have multiple causes, such as:

Excessive Humidity

Air conditioners not only cool your home; they dehumidify it as well. Besides making your home more comfortable, this also prevents condensation from forming along your vents and ductwork.

However, certain activities, like boiling water, taking hot showers, running the dishwasher, or drying clothes, release moisture into your home. At the same time, drafts let humid air sneak in through your doors and windows. Limiting these activities and sealing air leaks helps keep moisture levels under control and prevents condensation from forming on your AC vents.

Poor Insulation

Bare ducts are a magnet for condensation. If you’ve ever touched an AC duct, you know how cold they are. Insulating your ductwork creates a barrier between the cool metal and surrounding air, which prevents them from sweating. Depending on your situation, you may be able to resolve the problem without professional help. Purchase some R-11 or R-13 fiberglass rolls and wrap them around your exposed ducts. Duct boards, duct liners, and duct wrap are also effective solutions.

Leaky Boot

Ducts connect to vents through a tube called a boot. However, if the boot isn’t sealed or insulated properly, warm air can seep in. This is often the reason why vents “sweat.” Gaps between the wall and vent can also lead to the same outcome. In either case, the solution is simple. Seal the gaps with caulk and wrap the boot with fiberglass or duct liner.

Blocked Condensate Line

As stated earlier, air conditioners dehumidify the air in your home. This creates a lot of excess moisture inside your AC unit, which is supposed to collect in the drip pan and drain out the condensate line. However, if the line becomes clogged, water can overflow and trickle down into your vents.

Restricted Airflow

Air conditioners are much colder than you realize. When the refrigerant enters the evaporator, its temperature drops below freezing. Absorbing heat from the surrounding air keeps it at around 40°F while the AC is on, but only if there’s constant airflow. Reducing airflow lowers the temperature of the coils, causing condensation to freeze inside your air conditioner.

Frozen coils cause a lot of problems. Ice and low airflow make it harder for your AC system to dehumidify the air, leading to elevated moisture levels inside your home. At the same time, when the unit’s deactivated, melting ice can trickle down through your ductwork.

Restricted airflow is normally caused by dirty filters and blocked vents. If you haven’t changed your filter in the last three months, swap it out with a fresh one. Otherwise, check to make sure there aren’t many curtains or furniture around your return vents, which could keep air from circulating through your system. Finally, if neither remedy is working, call a technician to take a look at your air conditioner. The blower motor may be malfunctioning.

Low Refrigerant

Refrigerants are chemicals that absorb and dispel heat. They circulate constantly through your air conditioner, between the condenser and evaporator. In most cases, refrigerants never need to be recharged. Air conditioners are closed systems. With nowhere to go, refrigerants are designed to cycle endlessly until your air conditioner reaches the end of its lifespan.

However, refrigerants are stored under such intense pressure that occasionally they spring a leak ‒ a small rupture in the condenser or evaporator coils. Refrigerant leaks are rarely noticeable at first, but over time they gradually raise humidity levels in your home. With less refrigerant to cool the air, less condensation forms inside your air conditioner, which means more humidity is released into your ventilation system.

Low refrigerant isn’t a problem most homeowners can solve on their own. Only qualified HVAC technicians are allowed to handle and recharge refrigerants. If you believe your air conditioner has developed a leak, call a contractor right away to have it repaired.

Protecting Your Air Conditioner

Condensation on your AC vent is generally an inconvenience. However, it could also be a sign of a deeper problem. Repairing your air conditioner can cost hundreds, sometimes even thousands of dollars. Don’t take chances. Trust HomesentialTM to protect your home and finances.

HomesentialTM covers your heating, cooling, and electrical systems. The way it works is simple. Rather than handle the costs themselves, homeowners call us when something goes wrong. We hire a contractor and pay for the repair and replacement of all covered parts. There are no service fees or deductibles. We cover all repairs up to $1,000. You’re only responsible for overages and your low monthly premium. Sign up now for protection and peace of mind.