Finding a puddle near your indoor AC unit on a muggy Greensboro afternoon stops you cold. Is it serious? Is it safe to keep running the system? Most AC water leaks have a diagnosable cause, and several of the most common ones have a straightforward fix. We handle this call more than almost any other during Piedmont Triad summers, and asking the right questions quickly usually tells us exactly what went wrong.
What matters most right now is that you don’t ignore it. A slow drip that seems minor can quietly damage drywall, flooring, and your home’s air quality within a day or two. Here’s what’s likely happening and what to do next.
Why Your AC Produces Water in the First Place
Your air conditioner pulls warm, humid air from inside your home across a cold evaporator coil. As that warm air meets the cold surface, moisture condenses out of it. Much the same way a cold drink sweats on a hot day, that water drips into a drain pan and exits through a condensate drain line, usually a PVC pipe routed to a floor drain or outside. Under normal operation, this process is invisible and continuous.
Greensboro’s humid subtropical climate makes this a far more demanding job than it sounds. Average summer relative humidity here runs between 70% and 76%, and July highs regularly reach 89 to 90 degrees Fahrenheit with dew points that stay elevated through much of September. Your AC is pulling an enormous volume of moisture out of the air every single day. When the drainage path breaks down (and in this climate it tends to happen faster and more dramatically than elsewhere), that volume has nowhere to go.
The Most Common Reasons an AC Leaks Water Inside
Most water leak calls we get in the Greensboro area trace back to one of three causes. Knowing which one you’re dealing with determines whether you can address it yourself or need a technician today.
Clogged Condensate Drain Line
This is the single most frequent cause. Over time, dust, algae, and mold accumulate inside the PVC drain pipe until the buildup restricts or fully blocks water flow. Water then backs up into the drain pan until it overflows. In Greensboro’s humid summers, that algae growth happens faster than most homeowners expect. A technician can flush the line with a wet-dry vacuum or compressed air, and it’s one of the standard tasks in a preventive maintenance visit.
Dirty Air Filter Causing a Frozen Coil
A clogged air filter restricts airflow across the evaporator coil. Without enough warm air moving over it, the coil drops below freezing and ice builds up on the surface. When the system cycles off, all of that ice melts at once. The result is more water than the drain pan can handle. This one you can investigate yourself: pull the filter and look at it. If it’s visibly gray and clogged, replacing it is the right first step.
Low Refrigerant Charge
Refrigerant is what circulates through your system and keeps the evaporator coil cold. When the charge drops too low, pressure falls and the coil freezes over, producing the same melt-flood scenario as a dirty filter. Unlike a filter change, diagnosing and correcting a refrigerant issue requires a licensed technician. It also usually means there’s a leak somewhere in the refrigerant circuit that needs to be found and repaired, not just refilled.
Other Causes Worth Knowing
These come up less often but matter more when they do, particularly in older systems.
Cracked or Rusted Drain Pan
The drain pan sits directly beneath the evaporator coil and catches all condensate before it reaches the drain line. In systems 12 to 15 years old or older, the pan can develop rust, cracks, or holes. At that point it doesn’t matter how clear the drain line is. Water passes straight through to whatever surface is below. A visual inspection with a flashlight will usually reveal this quickly.
Failed Condensate Pump
In homes where the indoor air handler is installed in a basement or attic without gravity drainage, a small condensate pump moves the water up and out. When that pump fails, there’s nowhere for the water to go. If your system is in a space like this and water is backing up, the pump is the first thing to check.
Improper Unit Leveling
The indoor air handler needs to be mounted level, or very slightly tilted toward the drain, so water flows naturally in the right direction. A unit that’s off-level will cause the drain pan to overflow on one side from day one, regardless of how clear the drain line is. This is an installation issue rather than a maintenance one, but it’s worth knowing if you’ve had a leak since a new system was put in.
Is This an Emergency? How to Triage the Leak
The first step is the same no matter what you suspect: turn the system off at the thermostat. Continuing to run a leaking AC risks water damage to ceilings, floors, and drywall, and creates moisture conditions where mold can begin growing within 24 to 48 hours. This is a realistic outcome when standing water sits in a home with 70-plus percent ambient humidity.
Once the system is off, check the air filter. If it’s visibly clogged, replace it. If the evaporator coil has been frozen, don’t restart the system in cooling mode right away. Run it in fan-only mode or leave it off entirely for a few hours to let the coil thaw completely before restarting.
The situations that call for same-day service are:
- Water is actively pooling and isn’t slowing down after the system is off
- The drain pan is visibly cracked or rusted and can’t hold water at all
- You hear hissing or bubbling sounds near the indoor unit, which can indicate a refrigerant leak
- The system isn’t cooling even when it runs, suggesting a frozen coil or refrigerant issue
- A filter replacement doesn’t stop the leak after one full cooling cycle
When any of those conditions are present, waiting to see if it resolves on its own typically makes the repair more involved, not less.
How to Prevent AC Water Leaks Before They Start
Annual professional maintenance is the most reliable way to stay ahead of this problem. A thorough visit before peak cooling season covers the condensate drain line, drain pan condition, refrigerant charge, and evaporator coil cleaning. In Greensboro’s climate, where systems run hard from late spring through early fall and process extraordinary amounts of moisture, that yearly checkup often catches a partial drain clog before it becomes an overflow.
One upgrade worth asking about when your system is serviced is a float switch. It is a small safety device that mounts in the drain pan and automatically shuts the system down if the water level rises too high. It won’t fix the underlying problem, but it stops water from reaching your floors and walls while you wait for a technician. The cost is modest relative to the water damage it can help prevent, and it’s particularly valuable in attic installations where a slow leak can go unnoticed for days.
Changing your air filter on a consistent schedule (typically every 30 to 90 days depending on filter type and household conditions) eliminates one of the most common causes of frozen coils and overflow entirely. It’s the simplest thing a homeowner can do to protect the system between professional visits.
Getting Your AC Leak Diagnosed & Fixed in Greensboro
Relief Heating And Cooling has served Greensboro and the Piedmont Triad since 2007, and we handle AC water leaks as part of our emergency and same-day service offering. All work is performed by our own technicians, not subcontractors, and every job is backed by our 100% satisfaction guarantee. If you’re dealing with a leak right now or want to schedule a maintenance visit to keep this from happening, call us at (336) 559-7992 or book directly through our online scheduling.