The A/C condensation drain line, usually a 1/2" or 3/4" PVC pipe extending from the attic to an outside wall near the condenser, allows water and moisture to exit the A/C unit during the refrigeration process. It is typically characterized by a slow drip when the A/C is in use. However, due to its function, location, and dark, cold environment, it can become a breeding ground for algae, bugs, and critter nests, which can cause blockage in the drain line and an overflow in the drain pan, potentially damaging drywall in the ceiling.
One telltale sign that your A/C drain line is clogged is when the fan on the outside unit continues to spin, but you may not be getting much air from your unit. In this case, you can use the following tips to unclog your AC drain line in the attic.
As a safety precaution, always shut off power to the A/C unit before making adjustments or repairs.
In the attic, locate the main drain line near the blower motor, usually just below the secondary drain line. Many drain pans have a secondary drain pipe that enables water to exit the system to the outside, usually via a second drain pipe located on the upper outer wall, to protect against drain overflow. When precipitation exits from the secondary drain pipe on the outside wall, it's another sign that the main drain is clogged.
Remove the removable cap or plug on the main drain pipe, usually located at the top of the drain line or further down the pipeline on a threaded tee.
Insert a small funnel into the main drain pipe to prepare it for flushing and cleaning. The funnel will help prevent spillage as the disinfectant is poured down the pipe.
With the funnel securely positioned in the drain pipe, slowly pour a half gallon of regular household bleach down the drain. The bleach will kill any existing algae, while the odor will help freshen the pipe and deter unwanted bugs and critters from making their home in the pipes, especially during colder seasons when the unit is not in use.
For a chemical-free alternative, you could use white vinegar. Although vinegar is effective at killing algae, it may take longer to remove clogs. Pour six ounces of white vinegar slowly down the drain and repeat every few months to keep the drain clear.
After flushing the drain from the attic, place a shop vacuum over the outside drain hole to suction out any blockages. Alternatively, you could run a fish or wire clothes hanger down the drain to help clear the blockage.
For more stubborn clogs and buildup, you may need to repeat steps 5 and 6 a few times to clear the pipe. Repeat the process until the main drain line is clear and water no longer trickles from the secondary drain line.
Place the cap back on the main drain line and turn the A/C back on. You should notice the fan inside the outdoor unit spinning and air coming out. Water should also be exiting the main drain line in a steady drip.
Allow the A/C to run for about 15 minutes on the desired temperature setting. Afterward, if you'd like, check for accurate temperature with a thermometer by pointing it at the supply register closest to the inside A/C unit. If the temperature is off, it may be time for an A/C tune-up.
When unclogging your AC drain line in the attic, be sure to follow the manufacturer's safety recommendations to avoid damaging your system. When working with chlorine bleach, wear protective clothing, including a plastic apron, eyewear, rubber gloves, and possibly a face mask to avoid damaging your clothes, irritating your skin, and breathing in harmful fumes.
Keeping your A/C drain line clear is imperative for an efficient working system to help keep your home cool and avoid damaging your ceiling, which can cave during drain pan overflow and lead to costly repairs. According to our research, it is recommended that you use these tips to unclog your AC drain line in the attic at least once a year.
Trying these tips can help keep your A/C running efficiently this summer and your ceiling intact. After attempting these steps, be sure to inform us of your experience.