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Ambrose Air, Inc. has been a family-owned AC repair and HVAC company in Orlando for over 25 years. Our slogan, “Honesty and Quality at a Fair Price,” speaks directly to our aim of keeping our customers happy.

Clogged AC Condensate Drain

One of the most common Orlando AC Repair problems is when the condensate drain line is clogged. It’s important to regularly clean and maintain a home A/C air handler unit’s condensate drain pipe.

The condensation drain pipe that allows water to flow from the air handler’s drip pan to the outside of the home had become clogged with fungus, mildew, algae, debris and even small plants. The most important question is what causes the clogging?

What Causes A/C Condensate Drain Line Clogging?

A/C or heat pump condensate drains can become clogged, leading to condensate leaks, spillage, or even bacterial hazards in a building.

Clogged air conditioner condensate drain lines can form another source of air conditioner or heat pump condensate leakage that can in turn lead to hidden water damage or in some locations an indoor mold problem or bacterial contamination.

Our photograph of a nearly full A/C condensate overflow pan (at left) shows what can happen if the primary condensate air conditioner condensate drain line is clogged and worse, the condensate drain overflow pan is also itself clogged and not draining properly. Luckily we caught this attic mold and bacterial pond before it had soaked the ceilings below.

We see air conditioner or heat pump condensate drain lines clogging for several reasons:


Condensate trap debris dry-out cycle: Dust and debris or nearby insulation entering the condensate drain line trap near the air handler, often where the trap design includes a vertical standpipe open to the air, serving as an emergency overflow to prevent condensate from backing up inside the air handler itself.In months during which an air conditioning system is not in use, particularly for non-heat-pump systems that perform cooling-only, condensate and accumulated dust and debris that was resting in the condensate drain trap can convert to a dried plug of crud as the water portion of the condensate evaporates.After several years of this wet, sludge accumulation, and then drying cycle, the plug of dried sludge in a condensate trap or drain can actually block condensate flow through the system.


Improperly-installed condensate drain lines with a long near-horizontal run can allow dust and debris to accumulate, dry, and ultimately block condensate flow in the drain line


Insects, insect nests, or on larger piping systems, even rodents can clog a condensate drain line.


Condensate overflow pan drain blockage: dust and debris also accumulate readily in a condensate overflow pan where it can flow to and block the opening to the overflow pan’s independent condensate drain line. If a blockage occurs here, the condensate overflow pan may not do its job of preventing condensate spillage into the building.

How do I Clean an Air Conditioning or Heat Pump Condensate Drain?

Remove visible debris from the clogged air conditioning or heat pump condensate drain: start with a simple visual inspection. You may see a plug of crud blocking a condensate overflow pan right at its drain inlet – material that can be manually removed and the area wiped clean.Peering into the standpipe at a condensate drain trap, you may see crud right in that area that can be fished out or simply loosened and flushed through the drain line by working carefully so as not to break or loosen any pipe connections.Our photo (left) shows a poorly-installed A/C condensate drain system: the air handler condensate drain is installed in common with the overflow pan drain line – so that a blockage in the condensate drain line will guarantee that condensate spills onto the attic floor.The A/C condensate tray should have either had its own independent drain line, or it should have been installed with a sensor switch that shuts down the A/C or heat pump system if spillage is detected in the overflow pan. Finally, there is no trap on the condensate line and no air vent.Having a clogged drain is not the most expensive task on the list of AC Repair. If there is ever a concern, There are always many AC Repairmen readily available to assist.



Ambrose Air, Inc. has been a family-owned AC repair and HVAC company in Orlando for over 25 years. Our slogan, “Honesty and Quality at a Fair Price,” speaks directly to our aim of keeping our customers happy.