Home › Common Problems › AC Leaking Water Inside
AC Leaking Water Inside
in Portland, ME
Every AC system removes humidity from the air as it cools, and that water drains out through a small pipe called the condensate drain line. When that line gets plugged, water backs up and overflows the drain pan. Portland summers are humid, especially in July and August, which means the system is pulling a lot of water out of the air every day. A clogged drain can dump a significant amount of water before you even notice it.
Quick Answer
Water leaking from your indoor AC unit usually means the condensate drain is clogged. As the AC cools air, it pulls moisture out of it. That water needs somewhere to go. When the drain line gets blocked, water backs up and overflows. Portland homes with unfinished basements see this drain line clog with algae fast in summer. Call (207) 544-5500 before the overflow damages your floor or ceiling below.
Telltale Signs
Warning Signs to Watch For
- Water pooling on the floor directly under the indoor air handler
- Water stains on the ceiling below a second-floor air handler
- A musty or moldy smell coming from the air handler or vents
- The system shuts off by itself even though the thermostat is calling for cooling
- Visible rust or water marks on the outside of the air handler cabinet
Root Causes
What Causes AC Leaking Water Inside?
Clogged Condensate Drain Line
The drain line carries water from the drain pan to the outside of the house or to a floor drain. Algae and slime build up inside the line over the summer months, especially in Portland's humid July weather, and eventually block the flow completely. When the line blocks, the pan fills and overflows.
The Fix
Condensate Drain Line Flush
A tech uses a wet-vac and a cleaning solution to clear the line from the drain pan to the exit point. Adding a condensate pan tablet at the start of each season helps slow the algae growth.
Cracked or Rusted Drain Pan
The drain pan sits below the evaporator coil and catches condensation. In systems that are more than 15 years old, the steel pan can rust through and develop cracks. Portland's year-round humidity keeps the pan wet even when the AC isn't running, which speeds up rusting in older units.
The Fix
Drain Pan Replacement
A tech removes the old pan and installs a new one. Some units have a secondary emergency pan underneath as well, and both should be checked.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Clogged Condensate Drain Line | Cracked or Rusted Drain Pan |
|---|---|---|
| Water on the floor but drain line outlet outside is dry | ||
| Visible rust or holes in the pan below the coil | ||
| System shuts off on its own and pan is full of water | ||
| Musty smell and water leaking from an older unit | ||
| Water leak stops after drain line is cleared but returns in weeks |
Free Inspection
Get a Diagnosis in Portland
An on-site inspection is the only way to confirm which cause applies to your property. Free, no obligation.
(207) 544-5500Free on-site inspection
Written estimate before work starts
Serving Portland & surrounding areas
Other Problems
Services That Fix This
Also Helpful