When you're running your AC system in the sweltering Southern California heat and spot water leaking around the indoor unit, it's natural to feel a bit alarmed. Air conditioning systems do produce moisture as a byproduct of the cooling process, but in normal operation, that moisture should be contained and drain safely outside your home. If you're dealing with an AC system leaking water, there could be a simple fix—or something that needs professional attention to prevent bigger issues down the line.
As a homeowner, understanding why your AC system is leaking water can save you time, money, and stress. In this guide, we'll cover the basics, explore common causes, and share practical steps to troubleshoot and prevent it. Whether it's a frozen coil or a clogged line, we've got you covered with tips tailored for Inland Empire residents.
JUMP LINKS
- Is it Normal for an AC System to Leak Water?
- Common Causes of an AC System Leaking Water
- How to Fix an AC System Leak (DIY vs. Professional Repairs)
- Dangers of Ignoring an AC System Leak
- How to Prevent AC System Leaks in the Future
IS IT NORMAL FOR AN AC SYSTEM TO LEAK WATER?
It's completely normal for your AC system to produce some moisture—after all, one of its key jobs is to cool and dehumidify the air in your home, especially during those humid summer days in Southern California. But there's a big difference between everyday condensation and a true AC system leak that leaves puddles in your attic or spilling onto the floor.
Here's how the process works: As warm, humid air from your home is pulled into the air handler, it passes over the cold evaporator coil. This coil absorbs heat and pulls moisture from the air, causing water droplets to form on the coil's surface—like dew on a cold glass. That condensation drips into a drain pan below the coil and flows out through the condensate drain line to the outside of your home (often safely away from your foundation).
In a well-functioning system, you shouldn't see any water pooling indoors. If you do notice your AC system leaking water, it's a sign something's disrupting this process—whether it's restricted airflow, a blockage, or wear and tear. Spotting the difference early can help you address why your AC system is leaking water before it turns into a costly repair.
COMMON CAUSES OF AN AC SYSTEM LEAKING WATER
Below are the most common reasons homeowners experience AC systems leaking water indoors.
1. A FROZEN EVAPORATOR COIL
When the evaporator coil gets too cold, ice forms. Eventually, that ice melts and overflows the drain pan-resulting in leaks.
Causes of a frozen coil include:
2. Dirty coil
3. Blocked vents
4. Low refrigerant levels
A professional will need to diagnose the root cause.
2. DIRTY OR CLOGGED AIR FILTER
A dirty air filter is one of the simplest yet most overlooked reasons for an AC system leaking water. When the filter gets clogged with dust and debris, it limits airflow over the evaporator coil. This imbalance causes the coil to freeze (as mentioned above), and when the ice thaws, water spills out—turning a minor maintenance task into a messy leak.
In Southern California's dusty environment, filters can clog faster than you think. Check yours monthly during summer, and if it's the culprit behind why your AC system is leaking water, a quick swap might resolve it.
3. LOW REFRIGERANT LEVELS
Low refrigerant often from a slow leak in the system disrupts the cooling cycle, causing the evaporator coil to run too cold and freeze over. As the ice melts, you'll see water leaking from your AC system, sometimes accompanied by warm air blowing from the vents.
This isn't a DIY fix: Refrigerant is a regulated substance, and handling it requires EPA certification. If you notice hissing sounds or inconsistent cooling alongside the leak, it's time to call in an expert.
4. DAMAGED OR RUSTED DRAIN PAN
The drain pan under your evaporator coil catches all that condensation, but over time especially in humid or coastal areas like parts of Southern California—it can rust, crack, or warp. A compromised pan lets water seep out instead of directing it to the drain line, leading to visible leaks around your indoor unit.
Older units (10+ years) are prime suspects. Inspect for rust stains or cracks, but replacement usually needs a pro to avoid further damage.
5. IMPROPER AC SYSTEM INSTALLATION
If your system wasn't installed level or the drain line slopes correctly, gravity can't do its job—water backs up and overflows. Oversized or undersized units can also create uneven cooling and drainage issues, exacerbating leaks.
This is rarer in newer installs but worth checking if your AC system is relatively new and still leaking water. A technician can verify alignment during a service call.
6. BROKEN CONDENSATE PUMP (IF APPLICABLE)
Some homes (especially basements) require a condensate pump to push water upward and outside. If the pump fails, water backs up and spills around the unit.
7. A MALFUNCTIONING DRAIN PAN OR OVERFLOW SENSOR
If the drain pan cracks or the safety sensor fails to shut the system off when water rises too high, water will overflow—leading to leaks around your indoor unit.
8. A CLOGGED CONDENSATE LINE
Dirt, algae, and debris love to build up in the PVC condensate drain line, blocking the path for moisture to exit your home. When this happens, water backs up into the drain pan and spills out, often the most straightforward cause of an AC system leaking water.
It's common in our region due to hard water minerals and outdoor dust. A quick outdoor check might reveal standing water near the exit.
HOW TO FIX AN AC SYSTEM LEAK (DIY VS. PROFESSIONAL REPAIRS)
Some issues with an AC system leaking water can be checked at home—but others require a licensed technician.
DIY STEPS YOU CAN TRY
1. Replace the air filter if it’s dirty.
2. Clear the condensate line with a wet/dry vacuum or a vinegar flush.
3.Check the thermostat setting—very low temperatures can promote coil freeze-ups.
Ensure all supply vents are open and unobstructed.
WHEN TO CALL A PROFESSIONAL
1. Ice on the evaporator coil
2. Suspected refrigerant leak
3. Damaged or rusted drain pan
4. Broken condensate pump
5. Persistent clogging in the drain line
6. Any electrical or installation issues
For fast, reliable cooling help, contact our central AC repair team.
DANGERS OF IGNORING AN AC SYSTEM LEAK
It's tempting to grab a towel and keep going when you see your AC system leaking water, but putting it off can lead to serious headaches. Water damage to floors, ceilings, or drywall can run $500–$5,000 to fix, depending on the spread. Worse, standing moisture breeds mold and mildew, which triggers allergies, respiratory issues, and musty odors that linger.
An inefficient, leaking system also hikes your energy bills up to 20% more as it strains to cool your home. And in extreme cases, electrical shorts from water exposure could spark fires. Don't risk it! Address the AC system leaking water promptly for your home's health and your wallet.
HOW TO PREVENT AC SYSTEM LEAKS IN THE FUTURE
Prevention is the best way to avoid costly AC repairs and water damage.
1. Schedule regular AC maintenance - learn more here
2. Replace air filters every 1-3 months
3. Flush the condensate line with vinegar a few times a year
4. Keep vents open and unobstructed
5. Have annual professional tune-ups to keep your AC system operating safely and efficiently
With consistent care, your AC system can avoid leaks and last 15+ years.
NEED A TECH TO REPAIR YOUR LEAKY AC SYSTEM?
Dealing with an AC system leaking water doesn't have to disrupt your comfort especially when you've got experts on your side. At Burgeson's Heating, A/C, Electrical, Solar & Plumbing, we've served the Inland Empire for over 77 years, fixing hundreds of leaky AC systems safely and efficiently the first time.
Our team understands the unique challenges of Southern California's climate and can diagnose, repair, or maintain your unit to get you back to cool, dry air fast. Don't let a small leak turn into a big problem—contact us today for a consultation or emergency service. We're here to keep your home comfortable, one fix at a time.
