How to Clean AC Drain Lines and Prevent Future Clogs
There's nothing more draining than a broken AC, especially when it won't drain
When you’re thinking about the long list of to-dos in your home, it’s all too easy to forget your AC system, let alone your system’s drain line. However, it’s a vital part of an overall unit that helps keep you cool during the sweltering summer months. Luckily, learning how to clean an AC drain line is a rather simple process (and one you should do every three months or so).
What Is an AC Drain Line and Where Is It Located?
Your air conditioner works by passing warm air over an evaporator coil and sending a cool breeze flowing back into your living room. As the air plunges in temperature, condensation forms on the coil and drips into a condensate pan inside your home. Your AC drain line, often called a condensate drain line, carries the water from the pan to the outside.
You can find the AC drain line from the inside or outside of your home. Next to the indoor unit, look for a vertical pipe topped with a cap. That line runs throughout your home and eventually exits beside your outdoor unit, where you’ll see a white pipe or a copper pipe sticking out of your siding.
But what happens when something clogs this line? Dust, dirt, mildew, algae, and yes, even pet hair can end up in your drain line, causing the water to get backed up and drip all over the floor. A clogged AC drain line can also lead to a frozen evaporator coil and even cause your AC to shut off.
Learning how to clean your air conditioner can be the difference between a cool home and a sticky situation on a summer day.
Signs Your AC Drain Line Is Clogged
The AC drain line connects to the condensate pan at the bottom of your AC. No matter the type of system you have, you will almost always find these two parts at the base of your air conditioner. A PVC pipe or metal tube connected to the pan carries the condensation outside your home.
Because of where these parts are and what they’re made of, it’s not always easy to spot if the AC drain line is clogged just by looking at it. Instead, keep an eye, ear, and even your nose out for these telltale signs that something is holding up the works:
The drain pan is full
You notice condensation on your AC unit
Your evaporator coils are frozen
There’s mold around your AC or in the line
Your AC stops working
How to Clean an AC Drain Line Step by Step
Flushing your drain line is both a relatively quick DIY and a troubleshooting method to get your entire system in tip-top shape again. All you'll need is a bit of water, distilled vinegar, and rags at the ready.
1. Turn Off the Air Conditioner
Always turn off the power when dealing with complex electrical systems like air conditioners. Start by shutting down the thermostat, which should shut down the outside unit.
Don’t stop there. Next, head to your breaker box and flip the fuse lever associated with the AC system to the “off” position. Now, you’re ready to get to work.
2. Find the Condensate Drain Line
Before starting the cleaning process, find the drain line itself. The condensate drain line is a pipe located outside of your house, likely near the outdoor unit. Look for an inch-long PVC pipe that’s gray, white, or black and attached to your home's wall. Follow the PVC pipe to a drain pan at the end of the line.
Use dry rags to remove excess water in the pan before completing the next step. If you notice mold or bacteria in the pan, clean it with soap, water, and additional rags.
3. Look for the Access Point
Find the drain line’s access point, which is situated along the line and near the drain pan inside your home. Most drain lines feature vent tees (T-shaped pipes) with a cap or cover. Remove the cap, put on protective gloves, and inspect the interior for signs of a serious blockage.
If you spy large chunks of debris, remove them manually with your gloved hands or use a wire brush to break them up.
4. Flush the Drain Line With Distilled Vinegar
Now comes the fun part: flushing the drain line with distilled vinegar. This common pantry ingredient is a powerful acid that kills bacteria and mold and breaks down sludge and debris.
First, put on a face mask and eye protection, and keep wearing those gloves from the last step. Next, remove the drain line cap and pour around 1/4 cup of vinegar straight down the line. Let the vinegar sit undisturbed for at least 30 minutes, giving it time to work its magic. The longer you let it sit, the cleaner your line will be.
If no one has cleaned your drain line for some time or you notice foul smells, let the vinegar do its thing for a few hours before moving on to the next step.
5. Flush With Water
Once you’re certain the vinegar has kicked any mold growth to the curb, flush out the drain line with water. Just pour water straight into the drain line like you did with the vinegar, and keep an eye on the water flowing from the drain pan.
You don’t need to flush out the system for a long time, just long enough to ensure the line is clear. Once there’s no more gunk coming out of the line and the water is flowing out of the outdoor drain at a steady pace, you’re good to go.
6. Repeat as Needed
If the water doesn’t drain properly, your line is probably still clogged. You know what that means: It’s time to repeat the process. This time, let the vinegar sit for longer. Distilled vinegar will typically remove even the thickest clogs eventually.
Once you’re satisfied with the results, repeat the process every three months to ensure proper drainage. While you’re at it, consider performing other routine maintenance tasks, such as replacing air filters and removing debris from the outdoor unit.
5 Ways to Prevent Clogs in the Air Conditioner Drain Line
No one wants to discover a clogged drain line at the peak of a heat wave. And while we prefer to think of air conditioners as set-it-and-forget-it appliances, a bit of scheduled maintenance goes a long way. Here are five methods to keep your AC drain line from backing up:
Clean the drain line by walking through the steps above at least once every three months. If you live in a home with pets, increase the frequency to once a month.
Change or clean your air filter at least every one to three months. A dirty filter allows debris to build up in the rest of your system, including the drain line.
Schedule an AC inspection once a year to catch issues with your condensate pan, line, or evaporator coil before they start.
If flushing with vinegar doesn’t clear the AC drain line, the original builders may have improperly installed it. Call your local HVAC technician to take a look.
Consistently schedule AC maintenance on all parts of your AC system, not just the condensate lines and filters. Since all parts of your AC work in tandem, one problem can cause a domino effect of issues that keep it from cooling your home.
DIY vs. Hiring a Pro
Cleaning an AC drain line is a routine and DIY-friendly cleaning task suitable for inexperienced homeowners, so long as you wear gloves, eye protection, and a mask. If you notice telltale signs of a drain line blockage, such as water damage around the unit or a moldy smell in the air, give this process a try.
However, if multiple vinegar applications don’t address the clog, call a professional AC repair company near you for an inspection. HVAC repairs cost anywhere between $100 and $600, but addressing a condensate line only requires a quick visit since they’re experts in knowing how to clean an AC drain line. For the initial service call, technicians usually charge $100 to $250.
Lawrence Bonk contributed to this piece.
Frequently Asked Questions
Both bleach and vinegar make short work out of mold and bacteria, but vinegar is simply the safer choice here. For one, drain lines lead to your indoor system and your air vents, and inhaling bleach is bad for your health. Also, bleach is corrosive to some materials used in the manufacturing of drain lines, such as PVC.
If you have nearby access to a water hose and your AC drain line, the pressure from the hose can clear a small clog. Simply attach the end of a water hose to your drain line and flush water toward the outside of the house. Keep in mind, however, that you’ll need to use vinegar to break up more complicated clogs, such as thick layers of fur, algae, or mold.
Mold, algae, and debris commonly build up in AC drain lines every few months. If the drain line does become clogged, water will back up in the condensate drain pan. The water will then overflow and either affect the function of your AC or drip onto the floor, causing water damage around your system.
Clean your AC drain line every one to three months, depending on its tendency to clog. For example, if you live in a particularly humid area that’s prone to algae and mold growth, have an old home, or have several furry pets, clean your AC drain line as often as once a month. Be sure to keep up with the rest of your HVAC maintenance checklist as well, which can help you prevent clogs in your drain line.
Trapped water in your AC drain line is often a sign of a clog. There may be an area of debris blocking the flow of water from your drain pan to the line or out of the line itself. It’s also not normal to have an overflow of standing water in your drain pan. If this occurs, flush the line for blockages or call your local HVAC technician to investigate.