How to Clean a Clogged Primary AC Drain Line

A clogged primary AC (Air Conditioner) drain line won't just cause your AC to stop working, it could also cause costly and expensive water damage in your home. That's because this drain line takes excess water from the evaporator unit on your AC, the part located inside your house, and drains it outside. A clogged or backed up primary AC drain line will quickly cause the drain pan underneath your evaporator to overflow.

Remove mold or mildew that could be clogging your primary AC drain line.

Step 1

Cut the power to the air conditioner so you can work on it safely. You can do this in a number of ways. One way is by locating the main circuit breaker and cutting the power for the AC unit there. In other installations, the AC unit could be installed on a sub-breaker located on the exterior portion (the condenser) part of the unit. Lastly, if you can reach part of the AC unit, for example if it is installed in a hallway, you may be able to cut the power on the unit itself.

Step 2

Locate the primary AC drain line. These are typrically made out of PVC and will be routed to the outside of your house. Look for the outlet on the drain line and clear away any blockages, such as leaves or mud, that may be blocking the end.

Step 3

Locate the inlet of the primary AC drain line. These are connected to the drain pan that sits beneath the evaporator part of your unit. Common installation locations for these are in attics, basements or a hallway. The inlet on the primary AC line will be larger than the secondary AC drain line, if present.

Step 4

Clear out any water in the drain pan, if present. Small puddles can be wiped up with a towel or rags. Larger pools of water can be vacuumed up with a shop vac or similar device. Clearing out the water will allow you to more easily locate the clogged primary AC drain line.

Step 5

Use the brush to clear away any mold or mildew from the opening of the primary line. Insert the length of plastic tubing into the main drain line. Continue to feed the tubing into the line until you encounter the clog. Remove the clog by running the tubing forward and backward through the tube until the clog breaks up.

Step 6

Mix together a solution of one quarter cup of bleach to a gallon of warm water. Pour this down the drain line carefully. Allow this solution to sit for at least fifteen minutes, then flush by pouring cold water down the AC drain line. When the line is sucessfully cleared, you should see the bleach solution draining out of the oulet at the end of the drain line.

Step 7

Restore power to the AC unit.