If you’ve ever noticed water pooling around your air conditioner, you’re not alone. AC leaks are one of the most common problems homeowners face, and while they can look serious, they’re often simple to fix. The key is to identify the cause early before it leads to water damage or expensive repairs.

In this guide, you’ll learn why your AC is leaking, what you can do about it, and when it’s time to call a professional.

How AC Water Leakage Happens

Your air conditioner doesn’t just cool your home. It also removes humidity from the air. That moisture condenses on the evaporator coil, turns into water, and drains into a condensate pan. From there, the water flows through a drain line and safely exits the system.

When that process is interrupted, water can overflow or back up, leading to leaks. The most common causes include:

• Clogged drain line or drain pan
• Dirty air filter
• Frozen evaporator coil
• Cracked or rusted drain pan
• Faulty condensate pump
• Low refrigerant levels
• Poor installation or drainage slope

Let’s take a closer look at each one.

1. Clogged Drain Line or Drain Pan

What Happens

This is the most common cause of AC water leaks. Over time, dirt, dust, and algae can build up in the condensate drain line, blocking the water flow. When that happens, the water has nowhere to go and starts overflowing from the pan.

How to Diagnose

• Turn off your AC.
• Open the indoor unit and check if there’s standing water in the drain pan.
• Inspect the PVC drain line for clogs or a lack of water flow.

DIY Fix Steps

1. Turn off the AC power completely.
2. Mix ¼ cup of bleach with one quart of water and pour it into the drain line.
3. Use a wet/dry vacuum at the outside end of the line to suck out the clog.
4. Clean the drain pan with warm soapy water and a soft brush.
5. Turn the system back on and check if the leak has stopped.

If the clog keeps coming back, it might be time to call an AC technician to clean the line thoroughly.

2. Dirty or Clogged Air Filter

What Happens

A dirty air filter blocks airflow through your system. When airflow is restricted, the evaporator coil can freeze. Once it thaws, it creates more water than the drain pan can handle, causing leaks.

How to Diagnose

• Remove the air filter and check for heavy dust or debris.
• If the filter looks gray or feels clogged, it’s time for a replacement.
• Weak airflow from vents is another warning sign.

DIY Fix Steps

• Replace disposable filters or wash reusable ones.
• Always let reusable filters dry completely before reinstalling.
• Check filters every one to three months for best performance.

3. Frozen Evaporator Coil

What Happens

When the coil freezes, you might not notice a leak immediately. But once the ice melts, the sudden flow of water can overflow the drain pan. Low airflow, low refrigerant, or a dirty filter usually causes freezing.

How to Diagnose

• Open the indoor unit and look for ice or frost on the coil.
• Feel the refrigerant lines; if they’re icy cold, the coil is frozen.

DIY Fix Steps

• Turn off the system and let the ice melt naturally.
• Replace or clean the air filter to restore airflow.
• Once thawed, turn the AC back on and monitor it.
• If it freezes again, it may need professional service to check refrigerant levels.

4. Cracked or Rusted Drain Pan

What Happens

The drain pan collects the condensation from the coil. Over time, it can rust, crack, or warp, especially in older systems. Even a small crack can allow water to drip where it shouldn’t.

How to Diagnose

• Look for rust spots, holes, or cracks in the pan.
• If you see water dripping directly below the unit, that’s a strong indicator.

Fix Options

• Use a waterproof sealant or epoxy for small cracks.
• Replace the pan entirely if the damage is significant.
• Always make sure the new pan fits correctly and slopes toward the drain outlet.

5. Faulty Condensate Pump

What Happens

If your AC is in a basement or below ground level, it uses a pump to push water out. When the pump breaks or the float switch gets stuck, the water can back up and leak.

How to Diagnose

• Check if water is sitting inside the pump.
• Pour water into the pump reservoir; if it doesn’t activate, it may be faulty.

Fix Options

• Clean the pump and remove any debris.
• Replace the float switch if it’s not moving properly.
• If the pump motor fails, replace the pump entirely.

6. Low Refrigerant or Damaged Coil

What Happens

When the refrigerant is low, the pressure inside the system drops. This causes the coil to get too cold and freeze, leading to leaks once it melts. Corrosion or cracks in the coil can also lead to refrigerant loss and moisture buildup.

How to Diagnose

• Look for frost or ice on the coil or refrigerant lines.
• Notice if your AC is blowing warm air or taking longer to cool.

Fix Options

• Low refrigerant is not a DIY fix.
• A licensed HVAC technician must inspect, repair any leaks, and refill refrigerant safely.

7. Improper Installation or Poor Slope

What Happens

If the indoor unit or the drain line isn’t installed with the right slope, water can’t flow properly. This leads to pooling and leaks inside the unit.

How to Diagnose

• Visually check if the indoor unit appears tilted.
• Look at the drain line; it should have a steady downward slope.

Fix Options

• Adjust the position of the indoor unit so it leans slightly toward the drain line.
• Re-route or reattach the drain pipe if it’s sagging or improperly connected.

When You Can Fix It Yourself and When to Call a Pro

You Can Try These Fixes If:

• The problem is a clogged drain line, dirty filter, or minor drain pan crack.
• You have basic tools and can safely turn off the power.
• You’re comfortable checking the unit and performing light cleaning.

You Should Call a Professional If:

• The coil keeps freezing even after cleaning the filter.
• The refrigerant level is low.
• The condensate pump doesn’t work after cleaning.
• The problem returns after DIY efforts.

Step-by-Step Troubleshooting Checklist

1. Turn off the power to your AC.
2. Check and replace the air filter if it’s dirty.
3. Open the unit and inspect the drain pan for standing water.
4. Flush the drain line with a bleach and water solution.
5. Use a wet/dry vacuum to clear blockages.
6. Look for ice or frost on the coil and let it thaw.
7. Inspect the drain pan for cracks.
8. Test the condensate pump if present.
9. Turn the power back on and test the system.
10. If the leak continues, contact an HVAC technician.

Preventing Future AC Leaks

Preventing leaks is all about maintenance. Follow these simple habits to keep your system dry and efficient:

• Replace or clean filters regularly.
• Flush the condensate line every few months.
• Keep the area around the unit clear of dust and debris.
• Inspect the drain pan for rust or cracks.
• Schedule annual HVAC tune-ups.
• Watch for changes in cooling performance.

A clean and well-maintained system not only prevents leaks but also improves energy efficiency and extends your AC’s lifespan.

Want to learn more about common HVAC problems and how to prevent them? Read our post on Common HVAC Problems and How to Prevent Them to make sure your system stays in top shape.

An air conditioner leaking water can be alarming, but in most cases, the cause is simple and easy to fix. Clogged drain lines, dirty filters, and frozen coils are common issues that homeowners can handle on their own.

However, if you suspect refrigerant leaks, pump failure, or recurring water problems, it’s best to call a professional for an inspection.

Stay proactive, schedule regular maintenance, and your AC will keep your home cool, dry, and comfortable all season long.

A trained technician can test your system for leaks, check refrigerant pressure, and make safe, lasting repairs. Contact us today for a quote on maintenance and repair.