Stopping an air conditioner leak depends on the cause of the leak. Air conditioners may leak because of anything from a clogged condensate drain line to a dirty air filter. After discovering a leak, immediately turn off the air conditioner to prevent further leakage until the problem is determined.
The most common cause of an air conditioner leak is a clogged condensate drain line. Drain lines become clogged with anything from dust to mold, causing leaks in the home. To clear a clogged condensate line, use a wet/dry vac to suck out the blockage.
Another common cause for an air conditioner leak is a damaged drain pan. If an air conditioner is more than 12 years old, check the pan and replace if it shows signs of rust or damage.
A dirty air filter may block the airflow over the evaporator coil, causing a leak. Dust and dirt cause the coil to become too cold and freeze. The leak happens when it thaws. Make sure the air filter is clean and change it out every one to three months.
Low refrigerant may also cause an air conditioning unit to leak. Like the dirty air filter, when the Freon or refrigerant level gets too low, the evaporator coil freezes over and then thaws when there's not enough refrigerant in the system. Water leaking usually coincides with an air conditioner that is not cooling well or with a hissing or bubbling sound coming from the unit, which indicates a refrigerant leak.