Window Air Conditioner - Drain Plug
A window room air conditioner is not designed with a drain plug or drain hole that allows the unit to drain excess water while operating. Air conditioners have a "slinger ring" around the rear fan blade. The fan is designed to pick water up off the bottom of the pan and throw it against the condenser coils. This design feature helps improve the efficiency of the unit by reducing heat on the coils and helps remove some of the condensation and rain water from the pan.
Water will collect in the base pan and may even overflow and drip outside during periods of high humidity or on rainy days. This is normal operation.
Some room air conditioners appear to have a drain plug at the bottom of the pan. Under normal circumstances, this drain plug should not be removed. The drain plug allows water removal if the air conditioner is being stored for the season or if a technician needs to remove the water.
On a few newer model room air conditioners, there is a sub-base water plug. To ensure maximum efficiency it is recommended to check to ensure the rubber drain plug is properly inserted. This plug may be removed during operation to minimize water in the back of the unit; however, removing it will lower the efficiency of your unit. Water droplets being thrown against the outside coils can make a pinging noise. This helps cool the condenser. You can reduce this noise by removing the subbase water plug.