What happens if you don't clean your AC drain line?

Author: Ray Watsica  |  Last update: Wednesday, June 25, 2025

If the drain line gets blocked, you may experience reduced cooling efficiency, water leakage, frozen coils, Mold and mildew growth, and even a shutdown of your entire air conditioning system.

How often should you clean your AC drain line?

You should flush your AC drain line once every three months to keep it clear of debris and buildup. Keeping your AC drain line clean prevents clogs, backups, mold growth, and extra wear on your AC unit.

What are the symptoms of a clogged AC drain line?

Symptoms of a clogged air conditioner drain line

Water damage near the indoor unit, including rust on the bottom of the unit. Musty smell when the AC is running. Heat pump/AC not cooling house. Heat pump/AC not turning on.

How much does it cost to flush an AC drain line?

Flush Condensate Drain Line

The repair cost to have the drain line flushed runs between $75 to $250.

Is bleach or vinegar better for an AC drain line?

Please don't use bleach. It can eat away at the glue in the joints, causing leaks in your drain line. Hot water or 30% vinegar is best. Also, you can occasionally use a wet/dry vacuum to clear the line.

How to Unclog Your AC Drain Line (and Prevent It From Happening Again)

What is the best solution to clean AC drains?

Water and Dish Soap

Use a mixture of both to clean your AC drain line. The dish soap will help to break down the dirt and debris, while the water will flush it away. To use this method, mix a quart of water and a teaspoon of dish soap. Next, pour the mixture into the drain line and allow it to sit for several hours.

Will vinegar damage PVC pipe?

Effects on Metal and PVC Pipes

While harmless for most metal and PVC pipes, prolonged exposure to the acidic nature of vinegar might corrode certain metals, like copper. PVC pipes, on the other hand, can withstand these substances without damage.

What comes out of AC drain line?

The dehumidification process happens within the air handler (your AC's indoor unit). Air blows across the evaporator coil, where moisture condenses and drips into a drain pan. From there, the moisture travels outside your home via a pipe called a drain line.

Will hydrogen peroxide clean an AC drain line?

Vinegar or hydrogen peroxide

This can help break down the clog, making it easier to pass on its own. After the 30 minutes is up, flush the drain with water to ensure everything is flowing as it should.

How much water should drip from AC drain line?

It's completely normal for your AC to drain 5-20 gallons of water outside of your home (via the condensate drain). It's NOT normal for your AC to drain any amount of water inside your home (around your indoor AC unit).

Will the AC shut off if the drain is clogged?

If there is a clog in the drain unit of your air conditioner, it will create a mess for you. The operation of your AC will remain the same, but the drain pan will overflow, and float will switch the AC off. This condition can also cause some damage to your AC, but it will not affect its cooling capacity.

How long to vacuum an AC drain line?

Once you've located your drain line runoff:
  1. Attach the wet/dry vac hose to the end of the drain line.
  2. Wrap the duct tape or cloth towel around the vacuum mouth to make the connection to the drain line airtight (it won't remove the clog otherwise).
  3. Run the vacuum for 1–2 minutes and then switch it off.

How do you know if your condensate pipe is blocked?

Common condensate issues

Common ways to identify if your condensate pipe is blocked are listening for an unusual gurgling sound when the boiler attempts to start, or the boiler may repeatedly 'lock out' or stop working and display an EA code.

How long does it take for vinegar to clear AC drain line?

Ensure that the solution reaches as far as possible down the line. Let it sit for about 30 minutes to allow the vinegar to break down any buildup. Flush the Drain Line.

How do I know if my AC is draining properly?

These signs include:
  1. Dripping or standing water. Leaking water around the A/C unit is a clear sign that the drain pipe is blocked. ...
  2. Mold in your A/C drip pan. The presence of mold is a sign of water accumulation, even if the drip pan isn't holding water when you inspect your A/C unit. ...
  3. Standing water in the drip pan.

What is the gunk in AC drain line?

Before you panic, rest assured that white slime isn't uncommon. It's a biofilm composed mainly of bacteria called Zooglea. Zooglea forms a protective layer around itself, thriving in the dark, damp environment of your AC's drain pan.

What is the best cleaner for AC drain line?

Add ¼ cup of distilled vinegar to the drain line through the opening where the cap was removed. It's recommended you use regular distilled white vinegar, as the increased acidity boosts its cleaning properties. If you find the smell of vinegar foul, you can also use peroxide or hot water and a dash of dish soap.

Is Clorox or vinegar better for AC drain line?

Cleaning AC Drain Line

We recommend using vinegar instead of a bleach solution because bleach can cause corrosion if you have copper tubing in your AC's drain line. In addition, spilling bleach can ruin your carpet or clothing, whereas vinegar does not harm; it just leaves an odor.

What is the best way to unclog a AC drain line?

To unclog an AC drain line, turn off the power to the unit. Locate the drain line and use a wet/dry vacuum to suck out the clog. Flush the line with water using a garden hose or cup of water. Check and clean the drain pan under the indoor unit.

How much does it cost to unclog an AC drain line?

Average Unclog AC Drain Line Cost

Typical unclog ac drain line costs can range anywhere from $75-$250. In the case that the evaporator coil needs replacing, you are would pay between $400 to $950.

How do I know if my condensate line is clogged?

One of the most obvious signs is a puddle of water in your AC's drain pan, which proves the water isn't draining as it should. Other signs include: Standing water near your air conditioner's condenser unit. A moldy smell around the drain or from your system's vents and registers.

Why should you never use baking soda and vinegar to unclog a drain?

The fizzing reaction and gas created may help loosen some small blockages. However, it is not typically strong enough to break down larger clogs or remove hard-to-reach debris. As a result of the above facts, if you have a serious drain clog, using baking soda and vinegar is unlikely to be effective.

Will Clorox hurt PVC pipes?

You can pour bleach down the drain without worrying about the safety of your PVC pipes, but it can be dangerous if it combines with certain things trapped in the pipe, such as ammonia or vinegar. This can create poisonous gases, which can come back up the drain and affect your health.

Is bleach or vinegar better for drains?

Drain Line Material

Chlorine bleach can quickly eat away at not only the line but the glue and cement joining the line to the fittings and the condensation pan. If your drain line is PVC, stick to white distilled vinegar for clearing clogs and debris, particularly during winter.

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