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Here's How to Remove Air Conditioning Condenser Drain Clogs

The air handler or indoor air conditioning equipment holds the cooling system evaporator coil. As it removes heating from the aircondensate forms and calls into the drain pan below before exiting the HVAC system through the AC drain line. If condensate drain clogs exist within the condensate pan or drain line, this problem could cause poor AC unit performance and even water damage to your home and air conditioning system

clogged condensate drain line is an air conditioner problem that doesn’t always require professional HVAC service to fix. If your drain line is clogged, use these instructions to remove clogs and protect your unit as well as your house

Thomas & Galbraith explain why a clogged AC drain line might happen in your home and what you should do when it does. If you just can’t unclog your condensate line after trying these steps, contact us for air conditioner maintenance and repair service.

Clogged AC Drain Line? Here’s Why

A clogged condensate drain line is a common AC unit or air handler issue, but many Cincinnati homeowners don’t understand why clogs occur. As indoor air passes through the system and over the evaporator coil, airborne pollutants are carried into the unit and deposited on surfaces, including the coils and drain pan. Debris found within the air conditioning system can include pollen, pet dander, dust, dirt, and other contaminant particles. 

During the cooling process, moisture in the air condenses as temperatures drop, causing water vapor to convert into condensate. Condensate forms on the evaporator coils and eventually drips off, then is caught by the condensate pan below. As the water rolls off the coils, those pollutant particles come with it. 

The drain pan is connected to the AC drain line, which allows condensate to move out of the air conditioner -it drains into a floor drain located near the indoor units or outside the house. The debris particles can stick within the pipe or pan during this process, and when enough matter gathers clogs form. The wet environment and access to nutrients in pollutant particles can lead to mold and algae growth within the HVAC unit or drip pan, and these particles can also collect and create clogs in the drain line. 

Signs of Condensate Drain Line Clogs

If there is a clog in the drain line of your air conditioner or HVAC system, there will be signs to clue you in regarding the presence of clogs. When your drain line is clogged, you may notice: 

  • Wet Floors and Water Damage Around the Indoor Air Handler or HVAC System 
  • Drain Pan Is Full of Standing Water 
  • Musty Smells and Mold Odors From Vents in the Home 
  • Your Home Doesn’t Feel Cool Enough When the Air Conditioner Cycles 
  • Your Air Conditioner Won’t Even Turn On 

Yes, clogs within the drain line could stop your cooling system from turning on and cooling your home. Many HVAC models have float switches inside the drain pan. These floats rise as water levels within the pan increase. At a specific point, the float triggers, telling the HVAC system not to run the air conditioner, regardless of the temperature settings on the thermostat. If the air conditioning system were to continue cycling, more condensate would form and drip into the drain pan, eventually causing water to spill over the sides of the pan and leave surrounding areas all wet. 

How to Unclog Your Condensate Drain Line

Clogs occur within the drain pan that sits underneath the evaporator coil, or somewhere along the condensate drain pipe that extends out of the unit to a floor drain located near the HVAC system or to the exterior of the home. To unclog the drain line yourself, follow these instructions and you may be able to avoid waiting for a technician and paying to have your drain line cleared. 

1. Shut off power to your HVAC system. 

2. Open up the access door on the exterior of your air handler or furnace so that you can see the evaporator coil and the drain pan below it. If you have an indoor air handler, the coils are usually located at the air intake side. For furnaces, the coils are usually positioned on the side for outgoing air. 

3. If there is standing water in the drain pan, it needs to be removed. You can soak up water with towels or use a shop vac. Suction out water using a wet-dry vacuum until the pan is clear of condensate. 

4. Use vinegar or dish soap to clean the drain pan, removing mold, algae, dust, dirt, and other particles. Doing so will prevent future mold and algae development, as well as adding pan tablets.

5. Use a thin wire brush and insert it into the hole of the drain pan to clean off debris gathered in this area and remove any clogs sitting at this point. 

6. Follow the drain pipe that runs off the drain pan to locate the drain vent, which is a T-shaped section of pipe that comes off the main drain line. Take off the PVC cap and set it aside. Take the wire brush and insert it down into the pipe, cleaning away debris on the pipe walls. 

7. These methods can be used to unclog a clogged condensate drain at this access point: 

a. Run a plumber’s snake into the drain and down the pipe in the direction of its exit. Twist and remove to break through clogs and pull out debris if possible.

b. Attach the shop vac or wet-dry vacuum to this access point and use tape to make a seal. Turn on the vacuum and give it a few minutes to suction out clogs if possible.

c. Run a garden hose into the house and insert it into the pipe vent. Make sure to thread the hose down into the drain pipe towards its exit, not back in the direction of the air handler or indoor HVAC unit. Turn on the hose so that water flows through the AC drain line and out its exit point to flush out clogs if possible.

8. Locate the drain opening outdoors or near a floor drain located in the area. Take a brush and clean around the pipe opening to remove debris and material clogging the drain line at this point, such as a bird’s nest or leaves. The following methods can unclog drain lines at this point of access: 

a. Push the plumber’s snake up through the pipe opening. Turn the snake and remove it from the drain line to pull out any clog debris that has been caught.

b. Attach a wet-dry vacuum or shop vac hose to the end of the AC drain line, using tape to make a seal. Run the vacuum for a few minutes to suction clogs out of the line.

c. Hold a garden hose to the opening of the pipe with your hand. Spray the hose up into the drain line in quick bursts to break up clogs and flush debris out of the AC condensate drain.

9. Clean out the condensate line by flushing it with vinegar. Pour a cup of white distilled vinegar into the pipe vent access point. Cleaning the condensate drain with vinegar will kill bacteria, algae, and mold inside of it. Leave the vinegar to sit for several hours before you pour water into the access point to flush out the drain line. 

10. Flush the drain line with water at the vent. Have someone stand at the exit point of the AC drain line to look at how well or how poorly the drain pipe drains. If water flows cleanly out of the condensate drain pipe, the clog is likely gone. 

11. Put the PVC cap back on the drain vent. 

12. Reattach the panel to the exterior of your air handler or furnace. 

13. Turn on power to the HVAC system at the home’s electrical breaker box. 

If clogs do not come out of the drain line while performing these steps, you need the help of an HVAC professional to clear your clogged AC drain line. Contact Thomas & Galbraith to perform HVAC service that clears your drain lines and helps your air conditioner run efficiently.

Maintain Your Air Conditioner 

Unclog stubborn AC drain lines when annual cooling system maintenance is performed by your professional HVAC technician. This is just one of the many tasks included in AC maintenance tune-ups. When clogs occur during cooling season, HVAC service ensures the proper repairs are made so condensate can drain away from your air conditioner, preventing water damage to your home. Call Thomas & Galbraith today to schedule air conditioner maintenance and cooling system repair as needed. 

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