Remove the screws from the cover for the condensation coils at the top of the unit with a screwdriver. Remove the cover.
Inspect the connection for the drain line coming from the bottom of the condensation coils. Tighten any loose connections with a wrench.
Follow the drain line and check any connections along the way for leaks. Tighten the connections or remove any leaking tubes as necessary.
Locate the drain line opening outside the home. Remove the paper filter from the inside of a wet/dry vacuum and put the hose over the line. Cover the end of the hose with a rag and turn on the unit for about five seconds to remove any clogs from the line. Check to see if this stops the leak.
Pour a cup of bleach down the drain line access hole to kill any algae which may be growing and clogging the unit.