Short answer: Your AC pulls water out of the air and sends it down a condensate drain line. When water leaks inside, Carrier lists a clogged drain line as a main cause, followed by a cracked or rusted drain pan and a frozen evaporator coil (often from a dirty filter or low refrigerant). Turn the system off, dry the area, check the filter, the pan and the drain line.
Quick diagnosis
| What you notice | Most likely cause | What to check | Call a pro? |
|---|---|---|---|
| Water around the indoor unit or furnace | Clogged condensate drain line | Look at the drain outlet; is water coming out? | If you cannot clear it |
| Drip from a rusty or cracked pan | Damaged drain pan | Inspect the pan with a flashlight | Often |
| Ice on the coil or lines, water when it thaws | Frozen coil (dirty filter or low refrigerant) | Turn off, replace filter | If it refreezes |
| Water near a small pump with a tube | Failed condensate pump | Check the pump runs and is plugged in | Often |
| Water dripping from a ceiling vent | Condensation on ducts or a clogged attic unit drain | Check attic unit and pan | Yes |
Stop the damage first
- Turn the system off at the thermostat.
- Soak up the water and move anything that can be damaged.
- If water reached a ceiling, see our guide to a water stain on the ceiling: wet drywall can sag.
Clear the drain line
Find where the drain line exits (often outside near the condenser, or into a floor drain). Carrier suggests turning the AC off and using a wet-dry vacuum on the outdoor end of the line to pull out the clog. Do not use a wet-dry vacuum if you are not sure which line is the condensate drain.
Check that the line slopes downward all the way and that water flows freely once it is clear.
Check the filter and the pan
- Replace a dirty filter; Carrier suggests checking it monthly and replacing every one to three months.
- Look at the drain pan for cracks, rust or debris.
- If the coil is frozen, let it thaw with the system off before running it again.
When to call a professional
- You cannot find or clear the clog.
- The drain pan is cracked or rusted through.
- The coil freezes again after you replaced the filter.
- Water is coming through a ceiling or the leak may involve refrigerant.
What it usually costs
HomeGuide (2026) lists clearing a clogged condensate drain line at about $75 to $250 and a condensate pump at about $100 to $165. A service call is about $75 to $200.
Frequently asked questions
Is it normal for an AC to drip water?
Water should drip outside or into a drain. Water inside the house is not normal.
Can I keep running the AC while it leaks?
Carrier advises turning the system off. Pooling water can damage ceilings and floors and lead to mold.
Related problems
- AC not cooling
- Water stain on ceiling
- Mold on bathroom ceiling
- Thermostat not working
- Water leaking from ceiling
Sources
- Carrier: Why is my AC leaking water?
- HomeGuide: AC repair cost (2026)
- U.S. EPA: A brief guide to mold, moisture and your home
This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.