Residential AC Repair: Drain Line Clogs and How to Prevent Them from Causing Damage to Your Home

Homeownership is very complex; buying, selling, decorating, landscaping, maintaining . . . the list seems endless. One of the most important and most expensive building systems is your heating, ventilation, and air conditioning system (HVAC). The HVAC system makes living comfortably in modern homes possible, and that is never so apparent as during hot, steamy Texas summers.

The best way to extend the useful years of your HVAC system is by maintaining the component parts and we often share tips for keeping your system well-maintained. Since we still have several months in the cooling season left, here’s a tip for cleaning your condensation drain line.

What are you draining?

Air conditioning in most residences uses heat pump technology. The refrigerant gas is compressed, then quickly released. The compressed gas is very hot, but when released the hot gas gets very cold very fast. The release happens inside a chamber receiving hot air from your home. The gas cools the hot air and boy does that feel good?

A residual action happens because the hot air from your home is also humid. A good portion of the humidity collects on the network of tubes that carries the refrigerant gas like the water droplets that form outside of your glass of lemonade. Since the air conditioner removes several gallons of water every day, the condensation drain line removes the water outdoors or to a floor drain.

What’s the problem?

The water drops from the evaporator coil into a drain pan and at a certain level the water enters the drain line. The evaporator chamber is dark, with a huge volume of air moving through it. Some organic airborne particles move past the air filter, so in that cool, moist, dark area, algae will grow in both the drain pan and the drain line. If left unchecked, algae growth can cause problems and damage.

• The algae can smell really bad
• The air conditioner continues to remove humidity. With the drain line clogged, the drain pan will overflow into your home, damaging flooring, walls, furniture, and potentially the ceiling below a second-floor AC unit.

The clog is rather easy to prevent and easy to fix.

Preventing a clog.

The key to preventing algae growth is creating an environment inhospitable to the algae. The algae growth can be interrupted by abnormal pH levels. As a preventative maintenance task, add a cup of white vinegar into the drain pan. Vinegar is a mild acid and will retard or slow the growth of algae.

Clearing a clog.

If water is draining from under your central air conditioner, take a look around and identify the evaporator chamber and the drain line. The evaporator chamber will have fasteners to allow access; the drain line will be about 1” in diameter and lead to a floor drain or outdoors.

• Gather several tools: a screwdriver or ratchet, a wet/dry shop vacuum cleaner set for suctioning water.
• Find the circuit breaker in your electric service panel marked “AC,” and flip it to the off position.
• Open the evaporator chamber and take a look inside. Observe the evaporator coil—a network of copper or aluminum tubing, often in a “V” shape.
• Below the evaporator coil, observe the drain pan. It will probably be filled with water and perhaps debris. Use the shop vac and remove the water.
• Determine which end of the drain line is easiest to remove—the cabinet end or the floor drain end.
• Use the shop vac to suction the algae clog out of the drain line. It will be soft and easy to remove. However, you will need to anticipate a rush of water, so be prepared with the shop vac.
• Reconnect the drain line.
• Add a cup of vinegar to the drain pan. Refasten the cover and flip the circuit breaker to the On position.
• Vacuum the area surrounding the central air cabinet.

Observe the area for the next few days to ensure the clog has indeed been cleared.

Have a question about drain line clogs or Residential AC Repair?

For more information about R.M. Mullinix and Residential AC Repair, schedule an appointment, or visit our Residential AC Repair information page.