Why is my AC frozen or leaking water inside?
Prices and facts checked July 22, 2026.
A frozen AC and an AC leaking water indoors are usually the same story. The coil ices over from low airflow (a dirty filter) or low refrigerant (a leak), then when it thaws the melt overwhelms the drain pan and spills. The other cause is a clogged condensate drain line backing up on its own. Turn the system off to stop the water now, replace the filter, and let the coil thaw before you run it again.
Do this now to stop the damage
- Turn the system OFF at the thermostat, and turn the fan to ON. Off stops more ice from forming; the fan running helps the existing ice thaw faster.
- Mop up standing water and put a towel or shallow pan under the indoor unit. Water plus the electrical panel on the air handler is the real hazard here.
- Replace the air filter if it is dirty. Low airflow is the most common reason a coil freezes.
- Give it two to four hours to fully thaw before running cooling again. Running a still-frozen system just re-freezes it and can damage the compressor.
Which cause you are looking at
- Ice on the indoor coil or copper lines, house not cooling: frozen coil. If a new filter and a thaw fix it, you are done. If it re-freezes, it is low refrigerant from a leak, a pro visit.
- Water dripping or pooling with no ice: a clogged condensate drain line. Clearing the clog (a pro uses a wet-vac and a flush) is usually a modest visit, and many pros clear it as part of a tune-up.
- Cooling fading over days plus ice: low refrigerant. Ask the pro to find and fix the leak, not just recharge; refrigerant does not get used up.
Common questions
Why is my AC leaking water inside the house?
Most often a clogged condensate drain line backing up, or a frozen coil that thawed and overflowed the pan. Turn the system off to stop the leak, check and replace the filter, and if there is no ice the cause is usually the drain line, which a pro clears quickly.
Is it safe to run my AC if it is frozen?
No. Running a frozen system pushes liquid refrigerant toward the compressor and can damage it, an expensive repair. Turn cooling off, run the fan to thaw it, replace the filter, and only restart after it is fully thawed.
Can I fix a clogged AC drain line myself?
Sometimes. A wet/dry vac on the outdoor drain outlet can pull a soft clog, and a cup of distilled vinegar down the access port helps keep it clear. If it clogs again fast or you cannot find the line, a pro clears and inspects it.
Keep going
Sources
- ENERGY STAR maintenance guidance (airflow, filter, condensate drain)
- HomeAdvisor / Angi AC repair cost guides (2024) (drain clearing and refrigerant ranges)