How to tell if an AC drain is clogged?

Author: Earline Nolan III  |  Last update: Friday, October 24, 2025

A clogged AC drain line symptoms include:
  1. Musty, moldy smell near your indoor unit or in air from the registers/vents.
  2. Standing water near the indoor unit.
  3. Water damage in areas near the indoor unit.
  4. AC system is not cooling your home.
  5. AC system shuts down or doesn't turn on.

How do I check if my AC drain is clogged?

The easiest way to tell that your drain line is clogged is if you see water dripping out of the air handler, or you have standing water on the floor near the unit. If your air conditioner won't turn on, you should also open up the access door on the air handler to see if there is standing water in the drain pan.

What is the best way to unblock a condensate pipe?

Locate the white plastic pipe that leads outside, then check for any blockages like debris or ice. Defrost ice with warm water, not boiling, and use a rod or wire to push through the obstruction. If that doesn't work, call a pro with specialist equipment.

Will AC stop working if the drain is clogged?

Over time the drain line can become clogged and cause water to back up into your HVAC system, which can shut it down altogether. Follow these steps to check your HVAC system for clogs and remove them. Identify the Issue: When your AC malfunctions, it's crucial to diagnose the problem before considering a replacement.

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 to Check if Your AC Condensate Drain is Clogged

Is bleach or vinegar better for an AC drain line?

All right, so in summary, don't use bleach; use vinegar. That helps with any mildew growth—keeps you running clean. It's not going to actually clean your A/C drain, but it can prevent some backups.

How often should an AC drain line be cleaned?

You can prevent a clogged AC drain by performing routine cleaning. By pouring a ¼ cup of vinegar into your AC's drain line, you will kill any mold, algae, mildew, and other forms of bacteria or fungi, preventing it from forming a buildup and causing a clog. Repeat this monthly for the best results.

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

Flush Condensate Drain Line

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

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

How do you know if you have a blocked condensate pipe?

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 to clear an AC drain line without a vacuum?

Turn off your AC and remove the drain line from underneath by unscrewing the screws on its base. Then attach a hose to it and run water through it for several minutes or until all of the water comes out clean. This will cause water pressure in your drains to increase and push out any debris lodged inside them.

Why does my AC drain line keep clogging?

Dust is one of the most common causes of clogged air conditioner drains. As such, you must clean or replace your AC air filters to prevent dust from building up on the evaporator coils. Do this every few weeks to prevent blockage and keep your AC unit functioning effectively. Flush drain lines.

How long does it take to unclog an AC drain?

You can also try pouring a ¼ of a cup of white distilled vinegar (hydrogen peroxide or hot water and a bit of dish soap will also work) down the drain line access and let it sit for 30 minutes. That will help break down the clog and make it easier to vacuum out.

How do I know if my AC condenser is clogged?

This article will discuss five signs your AC condenser needs repair.
  1. Bad Smell. When an AC condenser unit stays for long without maintenance, it may start emanating a foul odor. ...
  2. Lack of Cool Air. ...
  3. Burning Smell. ...
  4. Lack of Airflow. ...
  5. Overheating While Idling. ...
  6. Bad Smell. ...
  7. Lack of Cool Air. ...
  8. Burning Smell.

What happens if water doesn't drain from the AC?

This will lead to standing water appearing around your indoor unit. If you notice this standing water right away, you can clean it up and get to work on trying to unclog an AC drain line. But if you don't, it could do water damage and allow mold to grow all around your AC unit.

How to tell if a 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.

What can I pour down my AC drain to unclog it?

Tips to Unclog Your AC's Drain Line
  1. Turn Off the AC's Power.
  2. Locate the Drain Pipe.
  3. Remove the Cap From the Pipe.
  4. Remove Any Visible Debris.
  5. Pour in Vinegar.
  6. Check to see if the AC Is Working as Expected.
  7. Finish Off With a Drain Pan Test.

Who to call for a clogged AC drain line?

Call Service Champions for Emergency AC Repair

We provide residential AC repair in San Jose, Sacramento, and other parts of Northern California. Call 833-600-0991 or schedule your visit online whether you need a condensate drain line unclogged, an AC thermostat repair, or an air conditioner replaced.

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

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 I put vinegar in an AC drain?

Repeating the vinegar cleaning process once every month will keep your AC drain line in great condition. The cleaning process is exceptionally effective at removing unwanted bacteria and fungi, allowing your AC to run efficiently.

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.

Can I snake a clogged AC drain line?

If you have a very stubborn clog that doesn't come out with a shop vac and water, then you can try using a drain snake. Push the drain snake down into the drain line access near the air handler. Make sure the that the drain snake does not go towards your air handler or you could potentially damage the evaporator coil.

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.

Do AC drain pan tablets work?

AC pan tablets work by releasing their active ingredients into the condensate water, where they effectively inhibit microbial growth and prevent mineral deposits. This helps keep the condensate pan clean and free from blockages, ensuring proper drainage and preventing potential water damage to the AC unit.

Previous article
Can you warm up soup in an air fryer?
Next article
Are glossy or matte tiles better for small bathrooms?