Clogged drains are a common cause of RV air conditioner leaks. To unclog the drain, turn off the air conditioner and locate the drain line. Use a wet/dry vacuum to suction out any debris or buildup in the drain line. Alternatively, you can use a pipe cleaner or long brush to remove any blockages. Once the drain is clear, pour a cup of bleach down the drain to kill any bacteria or mold.