Turn off the air conditioner and unplug the unit.
Open the air-conditioning unit by removing any screws to remove the casing. Inspect any tubes connected to the unit for leaks. Puddles beneath the tubing are an indication of a leak.
Replace the used tubing with new tubing. Un-clamp the hinges securing the used tubing with pliers. Reattach the replacement tubing with the hinges and pliers.
Remove the drain pan underneath the air-conditioning unit. Clean the pan with bleach and water to remove any dirt, dust and build-up in the pan. Reattach the pan.
Connect a wet-dry vacuum cleaner to the hose on the drain line. This line is located undr the drain pan. Turn on the vacuum cleaner at a low setting and allow the vacuum cleaner to suck the line to remove clogs in the line.
Locate the check valve near the unit's discharge tube. The check valve resembles a small ball. Unscrew the valve with a screwdriver and check the valve for imperfections and obstructions. Clean the valve with a cloth and reattach it.
Reassemble the air conditioner casing with the screws and screw driver. Plug in and turn on the air conditioner as per the manufacturer's instructions.