What will unclog an AC drain line?

Several safe and effective methods can completely unclog an air conditioner condensate drain line depending on the severity of the blockage. For minor clogs or routine maintenance, pouring a cup of warm water mixed with distilled white vinegar or three percent hydrogen peroxide down the indoor T-vent opening helps break down organic slime and algae. For stubborn, fully blocked lines, using a wet-dry shop vacuum on the outdoor exit pipe to create a tight seal and suck out the obstruction is one of the most reliable DIY techniques. Alternatively, professionals often use a specialized nitrogen tank or portable CO2 cartridge gun to send a controlled burst of pressurized gas through the pipe to blast the plug outward. You can also use a flexible plumber's snake or a dedicated HVAC drain brush for physical blockages, provided the PVC pipe has accessible straight sections that allow safe insertion without cracking the fittings.