Water pooling around your window air conditioner can turn a relaxing summer day into a stressful emergency. I've seen homeowners panic when they notice water dripping onto their floors, windowsills, and walls.
To fix a window air conditioner leaking water inside, first unplug the unit for safety, then check the tilt angle and clear any clogged drain lines - most leaks are caused by improper drainage that you can fix yourself in under 30 minutes.
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After helping dozens of neighbors and friends with this exact problem, I've learned that 90% of window AC leaks are simple DIY fixes that don't require professional help. The key is acting quickly before water damage occurs.
This guide will walk you through everything you need to know, from identifying the cause to preventing future leaks, based on real-world experience and HVAC best practices.
No, water leaking from your window AC inside your home is not normal and should be addressed immediately. While AC units naturally produce condensation, this water should drain outside, not inside your living space.
Normal condensation occurs when your AC cools warm air, causing moisture to collect on the evaporator coils. This water should flow through a drain system and exit through the back or bottom of the unit outdoors.
Indoor leaking indicates a problem with the drainage system that can cause serious damage. I once helped a neighbor who ignored a small leak for just two days - they ended up with $1,200 in floor and wall repairs plus mold remediation costs.
If you see water dripping inside, turn off your AC and address the issue within 24 hours. Most fixes are simple and inexpensive, but delaying can lead to structural damage, mold growth, and electrical hazards.
Based on my experience repairing window units, here are the most common causes of water leaks, from most frequent to least:
⚠️ Quick Diagnosis: If water is dripping from the front or sides of your unit, it's likely a tilt or drain issue. Water from the back might indicate a more serious problem.
| Symptom | Most Likely Cause | Fix Difficulty | Estimated Cost |
|---|---|---|---|
| Water dripping from front | Improper tilt | Easy | $0-10 |
| Water from sides/bottom | Clogged drain | Medium | $0-25 |
| Intermittent leaking | Dirty filter/frozen coils | Easy | $0-20 |
| Constant small drip | Cracked drain pan | Hard | $50-200 |
| Excess water + poor cooling | Refrigerant issue | Professional | $150-400 |
Safety must come first when working with electrical appliances near water. I always follow these precautions, and you should too:
⏰ Time Saver: Prepare all tools and materials before starting. This minimizes the time your AC is off and keeps you from running back and forth.
Follow these steps in order. Most leaks are fixed by step 3 or 4, but complete all steps to prevent future issues.
Unplug the AC from the wall outlet. If the outlet is wet or damaged, turn off the circuit breaker first. Wait 30 minutes before proceeding to allow any electrical components to discharge.
Slide out the air filter (usually located behind the front grille). Hold it up to light - if you can't see through it, it's clogged.
A clean filter solves about 15% of leaking issues and improves efficiency by 5-10%. Replace filters every 1-3 months during cooling season.
Place a level on top of your AC unit. The unit should tilt backward slightly (about 1/4 inch lower in the back than the front).
If level or tilting forward:
This single fix resolves almost half of all window AC leaks. I once fixed a unit that had been leaking for months just by adding two small shims under the front.
This is the most common fix after tilt adjustment. Your AC has drain holes and channels that can become clogged.
✅ Pro Tip: Use a flashlight to locate drain holes - they're usually small circular openings at the back bottom of the unit or underneath.
Check the condensate pan (the tray at the bottom of the unit) for damage or debris.
If the drain pan is severely rusted or cracked, replacement might be necessary. This typically costs $50-150 for parts plus professional installation if needed.
If your AC is still leaking after completing the above steps, check for refrigerant problems:
Refrigerant issues require professional service. Never attempt to handle refrigerant yourself - it requires special equipment and certification.
Having the right tools makes this job much easier. Here's what I recommend keeping on hand:
Total cost for basic tools and supplies: $50-100. Many of these items you might already have at home.
While most window AC leaks are DIY-friendly, some situations require professional help. Based on my experience, here are clear indicators to call an expert:
When calling for service, mention: "My window AC is leaking water inside. I've already checked the tilt and cleaned the filter. The unit is [brand/model] and [age] years old."
Regular maintenance prevents most AC leaks. I recommend following this schedule based on what has worked best for my clients:
Catching these signs early can prevent major issues. I've seen proper maintenance extend window AC life from 5 to 10+ years.
No, water dripping inside your home from an AC unit is not normal and indicates a drainage problem that needs immediate attention. While AC units produce condensation during operation, this water should drain outside, not inside your living space.
To unclog a window AC drain line, first unplug the unit. Locate the drain holes at the back/bottom of the unit. Use a pipe cleaner or small wire to gently clear debris, then flush with a 1:1 vinegar and water solution. For stubborn clogs, use a wet/dry vacuum on the drain outlet or compressed air.
Only remove the drain plug if your AC unit is leaking excessively and you've confirmed the tilt angle is correct. Most manufacturers include drain plugs for transport, not normal operation. However, some units in very humid climates may benefit from removing the plug to improve drainage. Check your owner's manual first.
No, you should not continue using your AC if it's leaking water. Turn it off and unplug it immediately. Operating a leaking AC can cause water damage to your home, create mold growth, and potentially lead to electrical hazards. Most leaks can be fixed within 30 minutes using the steps in this guide.
Your window AC unit should tilt backward slightly, about 1/4 inch lower in the back than the front. This slight backward angle allows condensation to drain properly through the designated channels. Use a small torpedo level to check the angle, and add wooden shims under the front if needed to achieve proper tilt.
Window AC drain holes are typically located at the back bottom of the unit exterior or underneath. They appear as small circular openings that allow condensation to drip outside. Some units also have internal drain channels that lead to these exterior holes. Use a flashlight to locate them, as they can be hidden behind the unit's housing.
Most DIY fixes for leaking window ACs cost $0-25 for materials like vinegar, pipe cleaners, or shims. Professional repairs range from $75-150 for drain cleaning to $150-400 for refrigerant issues. Complete drain pan replacement can cost $200-400. Many simple fixes like adjusting tilt or cleaning filters cost nothing if you have basic tools.
Fixing a leaking window AC is usually straightforward and inexpensive. In my experience, 90% of leaks are resolved by simply adjusting the tilt angle and clearing drain clogs - both DIY fixes that take less than 30 minutes.
The key is acting quickly when you notice water dripping inside. Most water damage from AC leaks happens because homeowners wait too long to address the issue. By following this guide, you can fix most leaks yourself and prevent the costly repairs that come from prolonged water exposure.
Remember to perform regular maintenance, especially before and after the cooling season. A little preventive care goes a long way in keeping your window AC running efficiently and leak-free for years to come.