It’s the middle of summer. You’re finally enjoying the cool comfort of your home when, drip, drip, drip, you notice water pooling under your air conditioner. Whether it’s a portable unit in the bedroom or a central AC system running all day, a leaking air conditioner is never something to ignore. But is it always a sign of trouble?
If you’ve spotted water dripping from your AC indoor unit or noticed your AC leaking water, you’re in the right place. This guide breaks down what’s normal, what’s not, and what you can do about it. We’ll walk you through the most common causes of a leaking AC unit, how to fix them, and when it’s time to call in the pros. Let’s dive in, minus the puddles.
Is it normal for an air conditioner to leak?
Short answer: Sometimes. But it depends on the situation.
Air conditioners work by removing heat and moisture from the air. That moisture turns into condensation and usually drains safely away. A little water isn’t always a red flag, but here’s how to tell what’s okay and what’s not:
Harmless condensation vs. a real leak
- Normal condensation: Light dripping from an outdoor unit on a humid day or a small amount of water in the drain pan is normal.
- Unusual water pooling indoors: Water dripping from the AC indoor unit or forming puddles around the base of your air conditioner is cause for concern.
When should you worry?
If you notice persistent puddles under your leaking AC unit, water stains near vents or ceiling (especially with central air), or your air conditioner dripping water from spots it normally doesn’t, it’s time to investigate.
Common causes of a leaking air conditioner
Several things can cause an AC to leak water. Most of them are related to blockages, damage, or improper maintenance.
1. Clogged condensate drain line
The condensate drain line removes moisture from your system. But it can easily get clogged with dust, mould, or algae, especially in humid environments. When it’s blocked, water backs up and overflows.
How to tell: You may hear gurgling, smell mustiness, or see water dripping from the unit indoors.
2. Cracked or overflowing drain pan
Over time, the drain pan under your evaporator coil can crack or rust, especially in older systems. If the pan is damaged or too full, it won’t hold the water that collects, leading to leaks.
3. Dirty air filters causing frozen coils
When air filters get clogged, airflow is restricted. This can cause the evaporator coils to freeze. Eventually, they thaw and release excess water too quickly for the pan to catch it, resulting in a leak.
4. Low refrigerant
Low refrigerant also leads to frozen coils. If your AC is low on refrigerant, it will overwork itself, causing the coils to ice up. Like dirty filters, this ends with too much meltwater at once, and hello puddles.
5. Improper installation or a unit that isn’t level
If your air conditioner isn’t level, the water may not drain properly and instead leak from the unit. This is especially common with window units or DIY portable setups.
Portable vs. central AC leaks: what’s different?
Not all AC systems are built the same. The way they leak, and how you fix them, depends on the type you’re using.
Portable air conditioners
Portable ACs often collect water in a tank or tray. If the tank is full and not emptied in time, water can spill out. Poor drainage setups or disconnected hoses can also cause a water leak in the air conditioner.
Fixes:
- Check the water tank and empty it regularly.
- Ensure the drainage hose is securely attached and angled properly.
- Use a gravity drain or condensate pump if your setup allows.
- Double check for cracks in the drain pan.
Central air conditioners
Leaks from central AC systems are more serious and often harder to access. Issues may include:
- Clogged condensate lines (common).
- Rusted or cracked attic drain pans.
- Leaks in ductwork (especially if the duct system runs through humid or uninsulated spaces).
Pro tip: Learn more about central air conditioning issues and fixes here.
How to fix a leaking air conditioner
Ready to get hands-on? Some AC leaks can be handled with simple DIY maintenance. Here’s where to start:
1. Clean or replace air filters
Dirty filters are a leading cause of frozen coils. Check your filters monthly, especially in summer, and clean or replace them as needed.
2. Flush the condensate drain line
Locate the drain line (usually a small PVC pipe) and use a wet/dry vacuum to suction out debris. You can also flush it with vinegar or a cleaning solution to prevent clogs.
3. Inspect and clean the drain pan
Check for cracks or rust in the drain pan. Clean it with a mild soap and warm water, and replace it if it’s damaged.
4. Straighten or level the unit
If you’re using a window AC or portable AC, make sure it’s level. Water should flow toward the drainage point, not pool inside the unit.
5. Defrost the coils
If your AC has frozen, turn it off and let it thaw. Place towels or a bucket underneath to catch any meltwater. Once thawed, clean the coils and check your filters.
When to call a professional
Some AC issues are best left to the experts. Call a technician if:
- You’ve tried the above fixes and your AC is still leaking water.
- You suspect a refrigerant leak (you might hear hissing or notice poor cooling).
- The leak has reached electrical components or damaged internal parts.
- The leak is damaging your walls, ceiling, or flooring.
Think it might be time to replace your AC? Explore your options in this handy guide:
Portable vs. window vs. mini-split air conditioner—Which should you choose?
How to prevent future leaks
A little routine maintenance can go a long way in keeping your AC drip-free.
1. Clean or replace filters monthly
It’s simple and it prevents many airflow and coil issues.
2. Flush the drain line seasonally
Clear any buildup with vinegar or a drain-cleaning solution to prevent clogs.
3. Schedule annual HVAC maintenance
A professional tune-up each year can catch issues before they become leaks.
4. Use a condensate pump
For setups where gravity drainage isn’t enough, especially with basements or central AC, a condensate pump can help move water away efficiently.
Wrapping up: No more puddles under your AC
A leaking air conditioner can be anything from a minor maintenance issue to a sign of a deeper problem. The key is to act quickly, identify the root cause, and know your limits. While many fixes are DIY-friendly, never hesitate to call a professional if you’re unsure.
Need a new AC that’s efficient, reliable, and leak-free? Shop the full range of air conditioners at Best Buy. Consult out our air conditioner buying guide for assistance in which type of model you best suit your home and needs, sizing advice, what features to consider, and more. And if you’re looking for more air conditioning tips, troubleshooting guides, or product comparisons, check out these helpful resources:
Stay cool and leak-free this summer!
