Where is the AC condensate drain line located?

In most homes, the condensate drain line is a small PVC pipe that runs from the indoor evaporator coil’s drain pan and exits the air handler to a drain—such as a floor or utility drain, a condensate pump, or the outdoors. The exact route depends on the type of air conditioning system you have.

What the condensate drain line does

The condensate drain line carries away water that forms when warm air passes over the evaporator coil. Proper drainage prevents water damage, mold growth, and overflow from the indoor unit. Most systems use a primary drain path and, in many installations, a secondary overflow path or an integrated condensate pump to handle backup drainage in case the primary line clogs.

• Primary condensate line: Typically a 3/4-inch to 1-inch PVC pipe that leaves the evaporator pan and travels to a floor drain, condensate pan, outside location, or a dedicated drainage point.


• Secondary/overflow line: A backup line or drain pan with a float switch in case the primary line clogs, directing water to a safe drain or triggering a pump.


• Trap and slope: The line is usually designed with a slight downward slope and may include a trap to prevent sewer gases from entering the living space.

Not all systems expose both lines; some rely on a condensate pump instead of a gravity drain, especially when the indoor unit is located above the drainage point.

Where it's typically located by system type

Where the condensate drain line appears depends on the system configuration. Here are the common setups you’re likely to encounter:

• Central air conditioning with a furnace/air handler: A PVC drain line usually exits the bottom or side of the air handler cabinet in a utility area (often a basement, garage, or closet) and runs to a floor drain, a utility sink, or outdoors.


• Ductless mini-split systems: Each indoor head has its own condensate line (often PVC) that exits near the head and runs to an outdoor drain or to a central drain line.


• Window or portable air conditioners: Drainage is often handled by a tray or reservoir with a drain hole at the bottom; some units route a hose to a nearby window, sump, or floor drain.

In all cases, look for a light-colored pipe, typically PVC, connected to the indoor unit or cabinet and routed toward the building’s drainage or outside area.

How to locate it in your home

Follow these steps to identify the condensate drain line in your space. This helps you inspect for blockages or leaks and understand your system’s drainage path.

1. Turn off the air conditioning and locate the indoor air handler or furnace/air handler cabinet. This is usually in a utility closet, basement, attic, or garage.


2. Look for a small white or clear PVC pipe coming from the bottom or side of the unit. Trace this pipe as it runs toward a drain, floor drain, or exterior location.


3. Check for a secondary overflow line nearby, which may be tied to a secondary drain, a drain pan, or a condensate pump if your system uses one.


4. If you can’t find a pipe, follow any visible drain tray or pan under the evaporator coil; the drain line often connects to that pan.


5. For ductless heads, inspect the indoor unit itself and the short length of pipe that exits the head, then follow it to its drainage point outside or to the central drain line.

Knowing the exact route of the drain line helps you detect issues early, such as blockages, leaks, or improper slope, and is a key step before performing any maintenance or flushing.

Maintenance and safety considerations

Regular attention to the condensate drain line helps prevent leaks and mold growth. Here are essential considerations to keep in mind.

• Inspect lines for cracks, disconnections, or signs of mold around the area where the line exits the unit.


• Ensure the line maintains a downward slope toward the drain and check for kinks or sharp bends that impede flow.


• Be aware of a secondary line or a condensate pump in systems that are not gravity-drained, and test the pump if present.


• If you suspect a clog or overflow, turn off the AC and contact a licensed HVAC technician to avoid water damage or electrical hazards.

Routine annual or semi-annual maintenance by a qualified technician can help maintain proper drainage, especially in homes with hard water deposits or algae growth in the lines.

Summary

Locating the AC condensate drain line typically means tracing a PVC pipe from the indoor evaporator coil or air handler to its drainage point, which could be a floor drain, outdoor outlet, or condensate pump. The exact path depends on whether you have a central system, a ductless mini-split, or a window/portable unit. Regular inspection for blockages, proper slope, and pump operation (if used) helps prevent leaks and water damage, and when in doubt, a licensed HVAC professional can locate and service the line safely.

Where does my AC drain line go outside?

The central AC drain line is typically a PVC pipe near the outdoor condenser unit or connected to the indoor evaporator coil's drain pan. Check for blockages caused by algae or debris, which can cause water backup and leaks. Use a wet/dry vacuum to clear clogs from the drain line's outdoor end.

How to unclog an AC condensate drain?

To unclog an AC condensate drain, turn off the power to the unit, locate the access cap on the drain line, and use a wet/dry vacuum or a garden hose to clear the clog. After physically removing as much debris as possible, pour about a cup of distilled vinegar into the line to kill mold and algae, wait 30 minutes, and then flush with water before reassembling and turning the power back on. 
This video demonstrates how to unclog an AC condensate drain line using a shop vacuum: 1mSilver CymbalYouTube · Aug 1, 2019
Step 1: Turn off the power 

• Switch off the power to your air conditioner both at the thermostat and at the breaker box. 

Step 2: Locate the drain line

• Find the drain line, which is typically a 3/4" PVC pipe coming from your indoor unit, and locate the access cap or T-shaped cleanout near the unit. 

You can watch this video to see how to locate the drain line and the access cap: 48sCreativeProcessDIYYouTube · Jul 28, 2025
Step 3: Remove the clog

• Option 1: Use a wet/dry vacuum: Use a wet/dry shop vacuum to suction out the clog from the outside end of the drain line. Create a seal by wrapping a rag around the pipe where it meets the vacuum hose. 
• Option 2: Use a garden hose: Insert a garden hose into the access point and flush the line with water. Block the back of the pipe to ensure water goes down the line, not back into the unit. 

This video shows how to use a shop vacuum to clear the clog: 58sWillman Air Heating and Air ConditioningYouTube · Apr 29, 2025
Step 4: Clear with vinegar 

• Pour about a cup of distilled vinegar into the access point of the drain line. 
• Allow the vinegar to sit for at least 30 minutes to kill any algae or mold that could be causing the clog. 

This video demonstrates how to pour vinegar into the AC drain line: 59sCreativeProcessDIYYouTube · Apr 18, 2025
Step 5: Flush and reassemble 

• After 30 minutes, flush the drain line with clean water to wash away the vinegar and any remaining debris. 
• Replace the drain cap and turn the power back on to your AC unit. 

Step 6: Check the drain pan 

• While you're at it, check the condensate pan for any standing water or debris and clean it out as well. 

What does a condensation pipe look like?

The condensate pipe is usually a white PVC-U pipe, similar to one you may find on a washing machine or sink waste pipe which usually goes outside into a drain.

How do I find my AC condensate drain line?

How do I find my AC drain line? Your AC has a condensate drain line running from the indoor to the outdoor unit. You'll find the end of the drain line somewhere near the outdoor unit (usually a copper or white PVC pipe). As for the access point, look for a vertical pipe with a cap near the indoor unit.