Water leaking inside from your AC is almost always caused by a clogged condensate drain line — by far the most common cause we see in South Florida. Other possibilities include a cracked drain pan, a coil that froze and is now thawing, or a unit that isn't level. Because so many Miami-area air handlers sit in attics or closets above living space, a leak here can cause real damage fast, so it's worth understanding what's actually happening.
Your AC removes humidity from the air as it cools, and that moisture has to go somewhere. It condenses on the evaporator coil and drips into a drain pan underneath, which feeds into a condensate drain line — usually a PVC pipe — that carries the water outside or to a floor drain. When that line is clear, you'd never notice this process happening at all.
That drain line clogs constantly in our climate because algae, mold, and mildew grow inside it year-round. South Florida's heat and humidity mean the system runs almost continuously for most of the year, and the warm, wet, dark inside of a condensate line is exactly the environment algae loves. Over months, a slimy buildup narrows the pipe until water backs up, overflows the drain pan, and drips into your ceiling, closet, or attic floor.
Many systems have a float switch specifically to prevent this kind of leak, and if your AC won't turn on at all, that switch may be the reason. The float switch sits in the drain pan or line and shuts the system off automatically when water rises too high, protecting your home from a bigger leak at the cost of your air conditioning. If your AC has water in the pan and won't start, don't force it back on — clear the clog first.
A cracked or rusted drain pan is a common cause in older units, especially metal pans that have been in service ten years or more. Once a pan cracks, water bypasses the drain line entirely and drips straight down regardless of whether the line itself is clear. This is a repair, not a DIY fix, since it usually means replacing the pan or, on an aging system, evaluating whether replacement of the whole unit makes more sense.
If you're comfortable doing a bit of maintenance yourself, you can often clear a partial clog before it becomes a full backup. Locate the drain line's outdoor termination point (usually a white PVC pipe dripping near the condenser) and use a wet/dry shop vacuum to pull the clog out from that end. Flushing a cup of distilled vinegar through the line's indoor access point every few months helps slow algae growth going forward.
If water is already visibly dripping from a ceiling, running down a wall, or pooling around the air handler, stop troubleshooting and turn the system off. Continuing to run the AC while it's actively leaking risks drywall damage, mold growth, and damage to flooring or belongings below an attic unit — repairs that cost far more than the AC problem itself. This is also a sign that a shop vac fix is a bandage, not a solution, if the clog is deeper in the line or the pan itself is compromised.
When a DIY flush doesn't solve it, or you can't find the outdoor drain termination, a licensed technician can clear the line properly and check the float switch, pan, and coil in one visit. Our AC repair technicians carry the tools to clear deep clogs, pressure-test the line, and diagnose whether a cracked pan or coil issue is contributing. For a broader troubleshooting checklist before you call, see our guide on what to check when your AC isn't working.
Water inside your home is not a wait-and-see problem. MGM A/C Appliances provides free estimates and 24/7 emergency service with no after-hours surcharge throughout Miami-Dade and Broward, including Homestead, Doral, and Coconut Grove. Call us at (786) 352-0084 and we'll clear the drain and stop the leak before it causes more damage.