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AC unit repair diagnosing problem when air conditioner fan is not working AC unit repair diagnosing problem when air conditioner fan is not working

How to Fix a Clogged AC Drain Line

During the heat of the summer, your HVAC system can work overtime to keep you cool and comfy. As it reduces the temperature, your air conditioning system also provides another important comfort benefit – pulling humidity from the air in your home. These vital functions take place around the evaporator coil, a cooling system component that is housed inside your home, mounted on or inside the air handler unit (furnace or fan coil).

As a part of the cooling process, moisture from condensation builds up on the evaporator coil and runs off into a condensate pan, then away from the indoor air handler unit through a drain line (often PVC pipe). If you get a drain line clog, water can build up and create havoc with your system, potentially causing it to shut down, or in more extreme cases, causing water damage to your home.

To prevent serious damage to your system or your home, be sure to contact a qualified HVAC technician when you see signs of a condensate drain pipe clog. A clogged AC drain line is a fairly common cause of system malfunction, and is often an easy issue to fix for a qualified HVAC service tech.

Also, you might be interested in visiting our air conditioner maintenance page for additional information regarding how you can help ensure that your AC works as intended and potentially reduce the risk of other future system issues.

Signs the AC Drain Line is Clogged

As indoor air circulates through the evaporator coil, dust, dirt and other airborne particles can be trapped by moisture. Build-up of this debris can be carried off as condensate drains from the coil. Over time, it can become trapped in your condensate drain line, causing blockage. As a preventative measure, many HVAC technicians will inspect and clear debris from the AC condensate drain during your annual maintenance tune-up. If this service isn’t done regularly, you could potentially experience a clogging issue.

AC drain line clogged [symptoms] include:

  • Musty, moldy smell near your indoor unit or in air from the registers/vents
  • Standing water near the indoor unit
  • Water damage in areas near the indoor unit
  • AC system is not cooling your home
  • AC system shuts down or doesn’t turn on

If you experience any of the above situations, it’s probably time to contact an HVAC professional who knows how to clear a clogged air conditioner drain line.

How to Unclog an AC Drain Line

Here’s what to expect when your HVAC tech arrives. Service of your HVAC equipment is best handled by a qualified professional.

Step 1 - Power Off the Air Conditioning Unit

When your HVAC services professional arrives to check your clogged AC drain line, they will likely turn the system’s power off, even if it is already not running. This is for the safety of the technician as well as to protect the HVAC system from additional condensate-related damage.

Step 2 - Check the Drain Pan

One of the first things the technician will do is locate the drain pain and check for standing water. If standing water is present, it can either be soaked up with rags or removed with a wet vac. The dry condensate pan should be thoroughly cleaned to help prevent the growth of mold.

Step 3 - Unclog the Drain Line

After physically removing any visible debris from the AC drain or drain pipe opening, the most likely way the technician will clear the clogged drain is using suction from a shop vacuum or wet vac. Alternatively, they might use a garden hose or plumbers snake to remove the clog. If successful, they should find a dark mass that was suctioned or pushed out of the drain line when they check the vacuum. They might also test that the line is clear by pouring a small amount of clean water through the drain and observing its ability to flow out.

Step 4 - Clean the Drain Line

Once the stoppage has been cleared out, the technician will likely follow up with a thorough cleaning of the drain pipe using a commercially available cleaner designed for use on PVC piping. If you ask, the technician may show you how you can pour a cup of a mild cleansing agent like distilled vinegar to occasionally give the drain a cleaning yourself between routine maintenance calls.

Step 5 - Finish Up

Once the drain has been cleaned and tested, your technician will reassemble or reinstall any parts removed, restore power to the system and check to be sure everything is functioning properly.

carrier HVAC technician ready to service outdoor air conditioner unit

Find an Air Conditioner Service Professional Near You

If you have a situation with a clogged air conditioner drain line and you have exhausted the troubleshooting steps outlined previously, it’s time to schedule an appointment with a certified HVAC technician. Your local Carrier HVAC dealer offers the expertise needed to properly diagnose and service your AC system.

Contact a Carrier HVAC Dealer
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