Check the condensation line. It's usually located outdoors, next to the compressor. The line is a PVC pipe that runs from the condenser inside your house to the outside, next to the compressor. The condensation drip from the condenser is carried from the inside to the outside. Check that the condensation is being removed; there should be a constant drip when the air conditioner is running.
Locate your condenser, which is usually in the attic. Some air conditioner condensers are located in closets or utility rooms. A drip pan is installed under the condenser unit to catch excessive drips or leaks. If you find water in the drip pan, clean or replace the condensation line.
Remove the cap from the indoor condensation line. If water overflows when you remove the cap, or if there is a constant drip, it's probably clogged. Look inside the condensation line to see if it's clogged with algae.
Clean the indoor line at the air conditioner condenser unit. Use a funnel to pour a warm water and bleach mixture into the line. Bleach will kill the algae and water will flush it out. Repeat up to three times to clear the clogged line.