Why Is My Air Conditioner Leaking Water?

If your air conditioner is leaking water, it’s usually due to one of these five common problems: a clogged condensate drain line, a dirty air filter, a frozen evaporator coil, low refrigerant, or a cracked drain pan. Each of these issues interferes with how your AC removes moisture from the air and if not addressed early, water leaks can lead to mold growth, water damage, or system failure. 

Let’s explore each cause in detail so you can better understand what’s happening and how to prevent future problems. 

1. Clogged Condensate Drain Line 

Your AC cools your home by pulling humidity from the air. That moisture collects and exits through a drain line. But over time, that line can become clogged with dirt, mold, or algae especially in humid environments or if maintenance is skipped. 

What Happens: 

Water backs up into the drain pan and eventually overflows into your home, often showing up as water near the indoor unit. 

What to Do: 

You can attempt to clear the line using vinegar or a shop vacuum. But for deep clogs or recurring leaks, professional attention is best. 

For ongoing cooling needs, consider upgrading to a new energy-efficient AC system. 

2. Dirty or Blocked Air Filter 

When filters are clogged with dust and debris, airflow across the evaporator coil slows down. That drop in airflow causes the coil to get too cold and eventually freeze. Once it thaws, excess water can leak into surrounding areas. 

Signs You’ll Notice: 

• Weak airflow from vents 
• Ice forming on indoor parts 
• Sudden puddles after system turns off 

How to Prevent It: 

Replace your air filter every 30 to 90 days, depending on how often you use your system. A clean filter also helps your AC run more efficiently. 

3. Frozen Evaporator Coil 

Your AC’s evaporator coil is meant to stay cold but not frozen. Freezing can happen if there’s low refrigerant or limited airflow due to a dirty filter or blocked vents. 

Why It’s a Problem: 

When the coil freezes and eventually defrosts, the water released often exceeds what the drain pan can handle causing leaks. 

What You Can Do: 

Shut off the system and allow the coil to thaw completely. If the issue returns, it may be time to upgrade to a newer, properly calibrated AC system that avoids freezing issues from the start. 

4. Cracked or Rusted Drain Pan 

Older units (typically 10+ years) often suffer from worn-out drain pans. Corrosion, cracks, or warping can cause water to leak out instead of draining properly. 

What to Look For: 

• Visible rust below your indoor unit 
• Water stains on ceilings or floors 
• Persistent leaking even with clear drain lines 

Why Replacement Makes Sense: 

While the pan can be replaced, if your AC is aging and showing signs of multiple issues, it may be more cost-effective to invest in a new system designed for efficiency and long-term reliability. 

5. Improper Installation or Unit Not Level 

For proper drainage, an AC unit must be slightly tilted toward the drain line. If installed incorrectly or if the unit has shifted over time, water may pool inside instead of draining, eventually leaking out. 

Common Scenarios: 

• Recent AC installation 
• Changes to flooring or attic platform 
• Water near the front of the indoor unit 

Fixing It: 

Installation mistakes often lead to recurring problems. A professional evaluation may reveal that a properly installed new unit would prevent leaks and improve overall comfort. 

Final Thoughts: Leaking May Be a Sign It’s Time to Upgrade 

While most AC water leaks can be repaired, repeated issues, especially in older systems, often signal that your cooling system is no longer running efficiently. 

At Go Lime, we help homeowners across Ontario stay cool with high-performance, professionally installed air conditioners built to handle local weather. Whether you're replacing an outdated system or upgrading to something more energy-efficient, we offer trusted installation backed by expert guidance. 
 

Book a free consultation to explore the best cooling solution for your home.