Finding your air conditioner leaking water can ruin your day, especially if you discover a puddle around your indoor unit or notice water dripping from your ceiling.
The good news? In many cases, the issue is repairable if it’s addressed quickly.
Your air conditioner naturally removes heat and moisture from the air as it cools your home. Under normal conditions, that condensation drains safely outside. But when something interferes with that process, your AC could start leaking.
In this guide, the HVAC experts at Comfort Zone Services explain why it happens, what you can check yourself, and when it’s time to call for professional air conditioner repair.
Is It Normal for an Air Conditioner to Produce Water?
Yes. In fact, according to research published in Case Studies in Chemical and Environmental Engineering (Matarneh, S., et al., 2024), the water production of an AC unit can range from 15 to 70L per day, depending on the humidity.
This is because as warm, humid indoor air passes over the evaporator coil, moisture condenses into water. It’s like how water droplets form on the outside of a cold drink on a hot day.
That water collects in a drain pan and then flows through a condensate drain line and safely outside your home.
If everything is working properly, you’ll never notice it. Problems occur when the water can’t drain the way it’s supposed to.
Why Is My Air Conditioner Leaking Water?
If you’re wondering, “Why is my air conditioner leaking water?”, one of these issues is usually the culprit.
1. A Clogged Condensate Drain Line
This is the most common cause of an air conditioner leaking water.
Over time, dirt, dust, algae, and debris can build up inside the drain line. Instead of draining outdoors, the water backs up into the drain pan until it overflows.
Signs include:
- Water pooling around the indoor unit
- Damp drywall or ceilings
- Musty odours
- Water damage near the furnace
Fortunately, this is usually a straightforward repair for an HVAC technician.
2. Dirty Air Filter
A clogged air filter doesn’t just reduce airflow; it can also lead to water leaks.
When airflow is restricted, the evaporator coil gets too cold and can freeze.
Eventually, the ice melts, which produces more water than the drain system is designed to handle, resulting in leaks.
Replacing your HVAC filter every one to three months is one of the easiest ways to prevent this problem.
To learn more about the different types of filters and schedule for changing them, read: “Here’s How Often to Change Your Furnace Filter.”
3. Frozen Evaporator Coil
A frozen evaporator coil is another common reason for an air conditioner leaking water inside.
Frozen coils may be caused by the aforementioned dirty air filters, as well as by blocked supply or return vents, low refrigerant levels, or blower motor problems.
Besides water leaks, you might also notice:
- Weak airflow
- Warm air coming from your vents
- Longer cooling cycles
- Ice visible on refrigerant lines
If you see ice, turn the system off and contact a professional for air conditioner repair services.
4. Cracked or Rusted Drain Pan
The drain pan sits beneath the indoor unit under the evaporator coil and collects condensation before directing it into the drain line.
Over time, older drain pans can rust, corrode, crack, or develop holes. When this happens, water leaks directly onto the floor instead of flowing into the drain.
Depending on the age of the system, sometimes fixing your AC leak could be as simple as replacing the drain pan.
5. Low AC Refrigerant
Low refrigerant doesn’t directly cause water leaks from the AC unit, but it often causes the evaporator coil to freeze. Once that ice melts, the excess water can overflow the drain pan.
If your refrigerant is low, you’ll probably notice higher energy bills, poor cooling performance, hissing sounds, or ice buildup on refrigerant lines.
Because refrigerant is contained within a sealed system, low refrigerant usually indicates a leak that requires professional repair.
6. Improper Installation
If your central air conditioner is leaking water shortly after installation, improper installation could be to blame.
This can happen if the unit isn’t level, the drain line was installed incorrectly, or there are loose drain connections.
If the system was recently installed, contact the HVAC contractor who completed the installation.
6. Broken Condensate Pump
Some air conditioning systems use a condensate pump to push water outside of your home. If the condensate pump fails, water will back up in the system, causing leaks.
Why Does My Furnace Leak When the Air Conditioner Is On?
Homeowners are sometimes concerned that their furnace leaks when the air conditioner is on. Your air conditioner’s evaporator coil is usually mounted directly above your furnace. The water you see around the furnace often isn’t coming from the furnace at all; it’s coming from the air conditioner.
A clogged drain line, cracked drain pan, or frozen evaporator coil can all allow water to drip onto or around the furnace cabinet, making it appear as though the furnace is leaking.
What Can You Check Yourself?
While many repairs should be left to a licensed HVAC technician, there are some things homeowners can do on their own, including:
- Replacing a dirty air filter.
- Checking that all supply and return vents are open.
- Looking for obvious water around the indoor unit.
- Inspecting the drain pan for visible cracks.
- Turning the system off if ice is forming.
Avoid attempting to disassemble your air conditioner or handle refrigerant yourself.
How to Prevent Your Air Conditioner from Leaking Water
The best way to prevent water leaks is through regular AC maintenance.
We recommend:
- Replacing your air filter every 1–3 months.
- Scheduling annual air conditioner maintenance before summer.
- Keeping outdoor equipment free of leaves and debris.
During routine maintenance, Comfort Zone technicians inspect and clean components, check the condensate drain system, test refrigerant levels, and identify small issues before they turn into expensive repairs.
When Should You Call for Air Conditioner Repair?
It’s time to call a professional for an air conditioner unit leaking water if:
- The leaking continues after replacing the air filter.
- Ice forms on the evaporator coil.
- The system isn’t cooling properly.
- Water is damaging your flooring, drywall, or ceiling.
- You suspect a refrigerant leak.
Ignoring the problem can lead to mould growth, water damage, reduced efficiency, and even complete system failure.
Get Expert Air Conditioner Repair in London, Ontario
Searching “air conditioner repair near me?” Whether your central air conditioner is leaking water, it seems like your furnace leaks when the air conditioner is on, or you’ve noticed water pooling around your indoor unit, Comfort Zone Services can help.
Our licensed technicians provide prompt, reliable air conditioner repair services throughout London and the surrounding area. We’ll identify the cause of the leak, explain your options, and get your system running properly again.
Contact us today to schedule your inspection.