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Clogged Condensate Drain Line & How to Fix 2023

Clogged Condensate Drain Line & How to Fix

Clogged Condensate Drain: Why It Happens and How to Deal 2023

This is the condensate drain, which plays an important role in removing condensation produced by your air conditioner’s evaporator coil. If the line isn’t properly cleaned, algae and mold can grow inside and clog the drain, causing elevated humidity, musty odors and water damage inside your home.

The primary condensate drain lines normally drain into the household sewer system through an open connection to an active p-trap.

In some cases, these active p-traps are the bathtub or bathroom sink p-trap; should this be your case, be sure to read the special instructions in maintenance, below.

Should the evaporator coil’s primary drain line become clogged or should the primary drain develop a leak, condensate should overflow or leak into the emergency drain pan thence into the emergency drain line?

Solution for a Clogged Kitchen Sink

The emergency condensate drain line, or drain pipe, drains to a conspicuous place outside the home.

Water dripping from the emergency drain line is a warning indicator that something is drastically wrong with the primary condensate drain system. You should not delay in calling a service technician.

Problems- With primary condensate drain lines stem from plant pollen, fungus spores, and other particulate matter entrained in the air stream passing over the wet evaporator coil.

They are captured by the condensate draining off the coil and are carried into the drain system. There they produce algae, mildew, and fungus growths which can clog the primary drainage system.

While the emergency drain lines are normally dry and clear, they are open to the atmosphere. Wasps, called “mud-daubers”, are known to nest in these open-drain lines, thereby rendering them useless; always at the wrong time.

The larger diameter pipe of the household sewer system yields two results. First, it usually precludes problems with condensation.

Second, the maintenance and repair beyond the open connection to the p-trap are outside the scope of the air conditioning technician.

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Clogged Condensate Drain Line & How to Fix 2023

Some older systems drain into an inactive p-trap; this can lead to the long term build-up of sediment, dried algae, etc… in the trap and result in an overflow of the plumbing drain system.

If the active p-trap also services a bathtub or bathroom sink, clogs can be caused by hair, soap scum, or other material draining from the tub or sink. Clogs in the household sewer system require the services of a licensed plumber.

Maintenance- Test both the primary and emergency drains with water. If a restriction is detected, he or she clears the obstruction with compressed air.

Blowing out a drain line will usually open a clogged drain line, but it cannot remove growing algae or other deposits from the pipe wall.

The technician will place algicide tablets in the primary drain pan. While algicide is used to prevent algae buildup, algicide kills any existing algae.

The dead algae may slough off the pipe wall and pass into the sewer system or drift downstream to a restriction and accumulate there resulting in a clogged drain.

Special Instructions- Bathtub or bathroom sink p-traps. If the active p-trap in your system is the trap for a bathtub or bathroom sink, there is the possibility that material flushed from the condensate drain system may combine with bathroom debris already in the trap, to begin the formation of a clog.

Should one of these plumbing drains clog, condensate will fill the sink or tub and overflow without any warning such as water dripping from the emergency drain line?

After any work on your condensate drain system, the drainage of the sink and tub should be observed. If either drains slowly or backs up, plumbing maintenance is needed.

Clogged Condensate Drain Line & How to Fix in 2023

Other measures the technician may recommend are the installation of a float switch in the emergency condensate drain pan and an Easy Klear clean-out valve.

Should both the primary and emergency drain systems fail, the float switch functions to turn off the air conditioning system, stopping the production of condensate until the clog is cleared and the drain pan emptied. Easy Klear helps improve drain line maintenance.

Despite all of these precautions, there can be no guarantee that your condensate drain system will remain clear.

Your condensate drain system can become clogged at any time and should be watched closely after it has been serviced, especially when algicide has been applied.

Older systems with accumulations of algae can become clogged anytime algae breaks loose from the pipe wall and drifts downstream to a restricted point.

At a restriction, algae will accumulate and grow unit it blocks the drain pipe. These restrictions can grow into a fully clogged drain line in less than one month.

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How to Repair Blocked Condensation Pipes of Your Air Conditioner?

Inside your air conditioner, air will condense into the water due to the heating and cooling process.

Therefore, if you take a closer look at your air conditioner, you can find a drain that runs from your air conditioner unit that releases the water to the outside. The condensation goes down a drain pipe that is usually white in color.

Many people panicked when they see water coming out from the condensation pipe. You do not need to worry about it. In fact, this shows that your air conditioner is working fine.

However, if you do not see water flowing out from the pipe, it is a good sign that the pipe is blocked. When the condensation pipe is blocked, water starts to leak from the ceiling and you start to see wet patches.

If the drainpipe of your air conditioner stops working completely, you will see water starting to leak down your wall and onto the floor.

To call for a technician to repair your drain pipe may be very expensive. If you want to save some money and are not afraid of the dirty work, you can actually do it on your own.

The first thing that you must do is to check the drains of your system. If you have a ducted air conditioner, head up to the roof and check the pipes. You need to make sure that the pipes are running downwards across the length of your roof, to the outside.

You will also need to make sure that there is nothing jamming the condensation pipes. Sometimes, sticks and insects clogged up the pipe.

Use a snake or wire to remove any solid particles inside the pipe. If there are algae that cannot be removed by your plastic snake, use a bleach solution to wash it away.

Once you have done all these, the condensation pipe should be clear.

To test it, run water down the pipes in the roof and have someone watching outside to make sure that the water flows smoothly down and out of the pipes.

If you are still having trouble, you should call a professional to come down and fix it for you.

For wall split or ductless units, you must go outside and run a wire or snake up the pipe to clear any solid particles. Again, if this does not solve the problem, you should engage a professional to help you.

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How to Clean Your Air Conditioner Drain

1. Turn off the power to your HVAC system at the thermostat and at the breaker.

2. If you have an indoor air handler in your attic or utility closet, you’ll need to find the condensate pan. This is usually located directly under the unit. It may also be covered by a removable access panel.

3. If you see standing water in the drain pan, your drain line is probably clogged. Use a handheld or shop vacuum to remove the moisture. You can also use rags to soak up the water. At this point, you can clean the drain pan with soap.

4. Generally, clogged drains can be cleared with suction. If you have a shop vacuum, use it to pull the clog through the drain opening, which is located outside your house near the foundation. Place your hand around the pipe to improve suction and allow the vacuum to run for a minute. Then, check the vacuum canister to see if the clog was successfully removed.

5. Next, you’ll need to identify the access point on the drain line. Usually, the drain will have a T-shaped vent with a PVC cover. Remove the cover and inspect the drain. Use this port to flush the drain with distilled vinegar. If you don’t like the odor, you can use peroxide to gently bubble away the remaining debris. Alternately, you can use hot water and a drop of dish liquid.

6. Allow the solution to sit for 30 minutes. Complete the cleaning by flushing the pipe with water. Have a helper watch the pipe outside and tell you if the water is running freely.

Clogged Condensate Drain: Why It Happens and How to Deal

If you don’t have a shop vacuum, you can use a piece of surgical tubing to free the blockage. Know that this method doesn’t work well if your drain line has sharp turns that are prone to clogs. If your system doesn’t have an access vent, use the opening on the edge of the drain pan. This fitting can be removed to improve access.

Underlying problems with the system can also be responsible for compromised water flow. If the pan and drain line aren’t slightly tilted, water can build up in the back of the pan and will eventually overflow. Many newer systems are equipped with overflow sensors installed within the pipe.

If you’re unable to clean your air conditioner’s drain line, call a local professional. They can clean the line and install an access vent, if necessary. Check the drain line periodically throughout the cooling season to ensure that condensation is being removed properly.

Routine maintenance steps like checking your drain line can help keep your air conditioner running more efficiently. If you find that your system is in need of repair, remember that an American Home Shield Home Warranty could help protect your budget from costs associated with getting your unit back on track. 


The AC condensate line in your Chamblee, GA, home plays a critical role in the indoor cooling process. The line is an exit route for moisture collected by the evaporator coil as air passes over it. The coil removes humidity from the air and converts it into water.

The water drains into the condensate drain pan, enters the drain line, travels down the drainpipe, and is deposited outside near the AC’s outdoor unit. It’s a simple process unless something goes wrong.

What Could Go Wrong With My AC Drain Line?

Over time, drain lines can get clogged with goo, gunk, dirt, rust, algae, microbes, and other sticky, unhealthy substances that block the flow of water from the evaporator coil to the exit pipe. That’s when the trouble starts.

What Can Happen With a Condensate Line Clog?

Several mishaps can occur with a blocked drain line:

  • Ice can form on the AC coils and inside the drain line. The ice can severely damage your air conditioning system.
  • Water in the drain pan can overflow and spill its contents inside your air conditioner.
  • Pools of water can collect on the floor near the indoor AC unit and wreak havoc on your floors, ceiling, carpeting, and furnishings.
  • Loose drain pipe fittings can cause leaks that damage your drywall or cause water to drip from your ceiling. Depending on where the AC unit is located and the severity of the leak, large areas of your home could be water-damaged.


  1. Turn off the power to your HVAC unit. …
  2. Find your AC drain line. …
  3. Push the stiff, thin brush into the end of the drain line. …
  4. Attach the end of your wet/dry vacuum to the end of the AC drain line. …
  5. After you’ve run the vacuum for about a minute, remove the wet/dry vac and head indoors. …
  6. Locate the vent tee.

Clogged Condensate Drain: Why It Happens and How to Deal

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