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Why Is My Air Conditioner Leaking Water Inside My House?

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Why Is My Air Conditioner Leaking Water Inside My House?

Published by Residential Heating and Cooling

Water leaking from your air conditioner may not seem like a big deal at first. However, it might end up being more than just a minor nuisance. That moisture can damage drywall, warp flooring, promote mold growth, and lead to expensive repairs if left unaddressed. Most importantly, it’s a sign that something inside your AC system isn’t working as it should.

At Residential Heating & Cooling, we believe in addressing problems before they spiral. If your air conditioner is leaking water inside the house, don’t panic. Here’s everything you need to know about leaky air conditioners, including when to call for help. 

How Your AC Normally Handles Water (And What Goes Wrong)

Air conditioners don’t just cool the air. They also remove humidity. As warm, moist air blows over the evaporator coil, the moisture condenses into water. This water is supposed to drain safely out of your home through a series of components:

Evaporator Coil → Drain Pan → Condensate Line → Outside

When everything is working, you may occasionally see a small trickle of water coming from the end of the drain line outside your home. That’s perfectly normal. It just means your AC is removing moisture from the air as intended. But when even one part of the drainage system fails, water can back up and overflow. 

Common Causes of AC Water Leaks

There are several possible reasons your air conditioner may be leaking water inside your home. Some are more obvious than others. Understanding these causes can help you spot the problem early and avoid major damage.

Routine Issues:

Clogged Condensate Drain Line

Over time, algae, dirt, and debris can clog the narrow PVC drain pipe, causing water to back up and overflow. This is one of the most common reasons homeowners notice leaks.

Cracked or Rusted Drain Pan

The metal or plastic pan that sits beneath the evaporator coil can crack or corrode over time. If this pan cannot hold water, the water will spill into your home instead.

Dirty Air Filter Causing Frozen Coils

Restricted airflow from a dirty filter can cause the coil to freeze. When it eventually thaws, it releases a large amount of water that can overwhelm the drain pan.

Less Common (But Important) Issues:

Refrigerant Imbalance

When your system is low on refrigerant, the evaporator coil can get too cold and freeze over. Eventually, that ice melts and floods the drain pan with more water than it’s designed to handle. If the pan overflows or the line can’t keep up, you’ll see water leaking inside the house.

Float Switch Failure

Many modern systems include a float switch that shuts off the unit when the drain pan fills. If it malfunctions, your system may keep running while leaking water.

Condensate Pump Problems

If your system is in a basement or below-grade area, it likely uses a pump to move water out. If this pump is broken, undersized, or miswired, water can spill over. 

Improper Installation Slope

Condensate drain lines must be properly sloped to allow gravity drainage. If they aren’t sloped properly, water will not drain properly, and your air conditioner may leak water. Poor installation is usually to blame for this situation.

Duct Condensation

If your ducts run through unconditioned spaces or aren’t sealed properly, they can “sweat” and drip water that appears as a leak around vents or ceiling openings.

When to Call for Help

It’s normal for your air conditioner to produce some water, especially during hot and humid weather. You might see a slow drip outside the home where the drain line ends. But if you see water anywhere inside your home, it’s time to get professional help.

Call an HVAC professional if you notice:

  • Water pooling around your indoor unit, vents, or ceilings
  • Moisture or stains near registers or in your attic/crawl space
  • Moldy or musty smells coming from your vents
  • Loud gurgling, bubbling, or dripping noises coming from your air conditioner
  • Sudden spikes in indoor humidity or a clammy feeling in your home
  • Weak airflow or rooms that don’t cool evenly
  • Frequent coil freezing or unexplained shutdowns of your AC system

At Residential Heating & Cooling, we respond to most emergency calls the same day. Chicagoland summers can be uncomfortably hot. If you suspect something might be wrong with your air conditioner, it’s best to reach out for professional AC repair

Get Peace of Mind With One Call

If you’re dealing with water where it shouldn’t be, don’t wait for the problem to get worse. Leaks can quickly lead to bigger issues like mold, water damage, and expensive repairs.

If you’re in the Chicagoland area, the trusted team at Residential Heating & Cooling is ready to help. Call us today to schedule an inspection. We’ll find out why your AC is leaking water and take the proper steps to fix it.


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