Attaching a wet-dry vacuum to the PVC drain outside the home quickly removes algae, dust, dirt and insects that tend to clog an air conditioner drain line. Most home improvement stores have a variety of fittings that allow the homeowner to attach the vacuum line to the drain securely. After about three minutes, the clogging debris and the water from the line and reservoir are clear.
Pouring approximately 3/4 cup of white vinegar into the drain line will also clear any bacteria growing inside. The acidity of the vinegar creates an environment where bacteria are unable to live. If the line is not draining, this method sometimes requires several hours. However, adding vinegar every few months is a good way to ensure the line remains clear. While bleach also kills bacteria, it is harmful to PVC pipe, joints and plants in the area where the vent drips, according to SF Gate.
The air conditioning system removes moisture from the air in the home. This water drips to a collection pan and then drains to the outside. A clogged line prevents the water from draining, so it backs up into the pan, eventually overflowing. If the unit is located inside the home, it can flood carpets and floors, causing a mess and damage. If the cooling is on in the home and the drain line is not dripping, algae and other debris are likely causing a clog.