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If you see water pooling around your indoor air handler or furnace, your AC has a drainage problem. Our technician Noah recently responded to a Duncan homeowner who noticed water soaking through the bedroom carpet. The culprit: a clogged condensate line on the upstairs air handler that had been silently overflowing into the drain pan, eventually overwhelming it and sending water through the ceiling into the room below. The pan was full, the carpet was soaked, and the homeowner had no idea anything was wrong until the stain appeared.
All air conditioners produce condensation as a normal part of the cooling process — but that water is supposed to drain away through a dedicated condensate line. When something blocks or breaks that drainage path, you get water where it shouldn’t be.
Here’s what our HVAC technicians look for.
Clogged Condensate Drain Line
This is the cause about 70% of the time. The condensate drain line is a PVC pipe (usually 3/4″) that carries water from the drain pan under the evaporator coil to a floor drain, exterior wall, or plumbing connection. Over time, algae, mold, and debris build up inside the line and block it. When the line can’t drain, the pan overflows.
Prevention: Pour a cup of white vinegar down the condensate drain line opening every 3 months during cooling season. This kills algae growth before it becomes a clog. The opening is usually a T-fitting or cap near the indoor air handler.
Fix: We clear clogged condensate lines with compressed nitrogen or a wet/dry vacuum. It takes about 15 minutes and is often included in a maintenance tune-up.
Frozen Evaporator Coil
When the evaporator coil freezes (usually due to low airflow from a dirty filter or low refrigerant), ice builds up on the coil. When the system cycles off or the ice begins to melt, it produces far more water than the drain pan can handle.
If you see ice on the refrigerant lines or the coil itself, turn the system to FAN ONLY and let it thaw completely before restarting. Check and replace the air filter. If the coil refreezes after a filter change, call a technician – you likely have a refrigerant issue.
Cracked or Rusted Drain Pan
The primary drain pan sits directly under the evaporator coil. In older systems (15+ years), metal drain pans can rust through, and plastic pans can crack. Water drips through the pan instead of flowing to the drain line.
Most systems also have a secondary (emergency) drain pan under the air handler itself, with a separate drain line. If you see water in the secondary pan, the primary drainage has failed and needs attention.
Disconnected Drain Line
Vibration from the air handler, improper installation, or work done near the unit can loosen or disconnect the condensate drain line. The water drains properly from the pan but spills at the disconnection point. This is a quick fix but can cause significant water damage if it goes unnoticed – especially when the air handler is in the attic.
Dirty Evaporator Coil
A coil coated in dust and debris doesn’t just reduce efficiency – it can disrupt the condensation flow pattern. Instead of water dripping down uniformly into the drain pan, it runs off the coil in unpredictable directions, potentially missing the pan entirely.
Coil cleaning is part of our annual maintenance service and prevents this issue.
When It’s an Emergency
Water leaking from an attic-mounted air handler is the most urgent scenario. Attic leaks can damage ceilings, insulation, drywall, and electrical wiring before you even notice the problem. If you see water stains on the ceiling below your air handler, call immediately.
Water around a basement or closet unit is less immediately damaging but still needs prompt attention to prevent mold growth and floor damage.
Preventive Maintenance Matters
Most AC water leaks are preventable with annual maintenance. During a Waldrop tune-up, we clean the drain line, inspect the drain pan, clean the coil, and verify proper drainage. This $150 service prevents thousands in potential water damage.
YOUTUBE EMBED: One Drain – Waldrop Plumbing Air Electric TV Commercial — @YallCallWally
Call Waldrop Plumbing Air Electric at (864) 536-0887 to schedule maintenance or an emergency repair.
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