A puddle near your indoor AC unit, a stain spreading across the ceiling, or water dripping from a vent — none of it is normal, and none of it should wait. Here’s what’s usually behind it.
Standing water only gets worse the longer it sits. If the towel-and-container fix buys you time, a same-day AC repair visit stops the source.
1. A Clogged Condensate Drain Line
Your AC pulls moisture out of the air as it cools, and that water is supposed to drain out through a condensate line. Algae, dirt, and debris build up inside that line over time and eventually block it completely — backing water up into the unit and, from there, into your home.
This is by far the most common cause, and it’s a quick fix for a technician with the right vacuum equipment.
2. A Frozen Evaporator Coil (That’s Now Thawing)
If airflow gets restricted — a dirty filter, blocked vents, or low refrigerant — the coil can ice over. You might not notice until it thaws and suddenly produces far more water than the drain line can handle, overflowing the drain pan.
3. A Cracked or Rusted Drain Pan
The pan that catches condensation under the indoor coil can crack or rust through with age, especially in older systems. Once it’s compromised, water leaks straight down instead of draining where it’s supposed to.
4. Improper Installation
If the indoor unit wasn’t installed level, or the drain line wasn’t pitched correctly, water won’t drain properly even when everything else is working fine.
What to Do Right Now
Turn off the system at the thermostat to stop more water from being produced, and place a towel or container to catch what’s already draining. Then call — the longer standing water sits, the more likely it damages flooring, drywall, or grows mold.