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Here's How to Remove Condensate Drain Clogs

The air handler or furnace connected to your heat pump or air conditioning system shouldn’t leak water out onto the floor. While it is normal for condensate to form on the evaporator coil during the cooling process, this moisture should be caught by the condensate drain pan and drained out of the HVAC system by the AC drain line. When your AC unit has a clogged condensate drain line, your HVAC equipment and indoor areas located near your indoor air handler or air conditioning system can become wet and even suffer water damage.

If your HVAC drain line is clogged, this problem needs to be corrected right away. Running your air conditioner with standing water in the drain pan and clogs in the AC condensate drain forces your system to operate with lower energy efficiency, disrupts cooling inside the house, and leads to damage to your home.

Jarboe’s Heating, Cooling & Plumbing explains how to remove condensate drain clogs without a call to our HVAC service team. Find out what to do remove clogs in the drain line and how to care for your condensate drain.

Reasons Why You Have a Clogged Condensate Drain Line

When you know the ins and outs of the cooling process, it’s fairly easy to understand how clogs can form in the condensate drain line of an air conditioning system. Indoor air can be heavy with pollutants including dust, dirt, pollen, dander, and other particulate matter. When this air moves into the air handler or furnace for cooling, it brings those particles along for the ride.

When air is cooled by refrigerant inside the evaporator coil, the moisture inside condenses. As vapor turns to liquid, condensate forms on the coils. This water also traps those airborne pollutants and drags them to surfaces inside the AC unit, such as the coils or even the pan below. Dripping condensate carries debris to the drain pan and the normal flow of condensate out of the HVAC unit carries those particles into the AC drain line. This debris paired with the wet conditions inside the air conditioner can fuel mold development in the HVAC system and algae growth in the drain pan.

If Your Drain Line Is Clogged, You May Notice These Signs

A clog to the condensate drain line produces a range of uncomfortable issues for Louisville homeowners. When debris stops condensate from exiting the AC drain line, you may notice these signs:

  • Wet floors and areas located near the indoor air handler or furnace.
  • Walls, floors, and other surfaces sustain water damage.
  • You see standing water in the condensate drain pan.
  • The home doesn’t feel as cool as it should while the air conditioner runs.
  • Vents give off an odor of mustiness and mold.
  • The air conditioner fails to start up when called for.

A clogged condensate drain may not sound like a serious HVAC problem, but it does have the potential to stop your AC unit from running and cooling your home when you need it most. This is due to a safety feature found in some drain pans. A float switch monitors the water level inside the drain pan, rising as more condensate falls into the drain pan and stays trapped within. If the float reaches a set point, it tells the air conditioner not to run until the float lowers. It doesn’t matter what your thermostat says, there will be no new cooling in your home.

Why does the float switch do this to your air conditioner? It’s simple. If cooling cycles were permitted to continue, the water level inside the drain pan would eventually get so high that water would spill out o the drain pan, onto floors surrounding the unit. This can quickly cause water damage to your home and your HVAC system.

Unclog a Clogged Condensate Drain Line

If there is a clog in the condensate drain system, it may sit near the drain pan or somewhere throughout the drain pipe that runs between the indoor furnace or air handler unit and either the outdoors or a floor drain near the HVAC system. Try these steps to remove clogs before you call us for HVAC service.

  1. Disconnect power to the air conditioner by flipping the breaker.
  2. Take off the panel covering the evaporator coil on your air handler or furnace. If you have an air handler, look for the evaporator coil along the intake air side of the unit. If you have a furnace, look for the coil at the air outtake of the system.
  3. Check the drain pan – if there is standing water, you need to remove it. Soak up water using towels or suction it out with a wet-dry shop vac.
  4. After the water is completely removed from the pan, use vinegar or dish detergent to wash out the pan. Doing so removes debris and mold while also helping to prevent mold growth within the pan in the future. Pan tablets can be placed within to help keep the component clean between maintenance visits.
  5. Clean around the drain hole where the drain pan connects to the AC drain line.
  6. Follow the condensate drain line running from the drain pan out of the unit. There will be a vent pipe that has a T shape coming off the main pipe of the AC condensate drain. Pull off the PVC cap and set it aside. Reach down into the vent opening with a wire brush to clean and remove debris clogging the vent. At the vent, you are able to use a few different methods for clog removal.
  7. Thread a plumbing snake into the drain vent toward the exit point of the condensate drain line. Wiggle the snake and pull it out to remove trapped debris.
  8. Connect a shop vacuum or wet-dry vac to the vent, forming a seal using tape. Run the vacuum for several minutes as you attempt to suction away any clogs in the drain.
  9. Stick a hose down inside the vent and position it in the section of pipe leading to the outdoors or nearby drain. Turn on the water for a few minutes to flush clogs out the exit of the drain line.
  10. Go outside or to the floor drain located by the HVAC system. Clean away any debris you find at the opening of the pipe which could be responsible for a clog. Try these methods to remove clogs sitting up within this AC drain line.
  11. Use the plumbing snake down the pipe. Move it around and remove to pull out any clogs.
  12. Connect the wet-dry vac or shop vacuum to this exterior access point and turn it on. Hold the vacuum hose tight to the condensate drain line using tape or your hands.
  13. Put a hose at the end of the drain line and hold it firmly with your hand. Turn on the water in short blasts that last no more than a few seconds. It is intended to force clogs to break up and flush out to the home’s exterior.
  14. Clean out the condensate AC drain line. Pour a cup of distilled vinegar into the pipe vent. Let the vinegar sit for an hour or more then pour one cup down the vent to rinse the drain line.
  15. Pour more water in through the vent while someone looks closely at the condensation drain line to make sure water freely pours out. If it does, your efforts to unclog the drain line were successful.
  16. Reinstall the PVC cap on the drain vent, replace the panel door on your air handler or heat pump, the flip power back on at the breaker.

With these procedures, you will likely be able to unclog a clogged condensate drain line on your own. If you prefer to leave the job to a professional or were unable to free the clog in your condensate line, go ahead and call your HVAC technician for help.

Prevent Condensate Line Clogs in Louisville

Regular maintenance is an important way to prevent clogs in AC drain line pipes and remove any existing clogs before they cause problems with your air conditioner. Have a professional HVAC service technician complete an air conditioner tune-up for your cooling system each year. Assessing the condensate drain system and clearing out any clogs is just one area that tune-up services focus on.

Jarboe’s Heating, Cooling & Plumbing keeps your Louisville air conditioner draining correctly. If you are unable to remove clogs from home AC unit condensate lines, give us a call! Our technicians are happy to come out and examine your condensate lines as well as remove any clogs we find in the cooling system.

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