What is the best tool for blowing out an AC drain line?

The best and most effective tool for blowing out a severely clogged air conditioner condensate drain line is a specialized HVAC nitrogen tank with a pressure regulator or a portable pressurized CO2 drain gun kit. Nitrogen and CO2 kits allow technicians and homeowners to send a controlled, high-pressure burst of gas through the PVC pipe, which instantly shatters and forces out stubborn plugs of algae, mold, and sludge that cannot be removed by simple flushing. Another fantastic, highly accessible tool is a heavy-duty wet-dry shop vacuum, which is typically used from the outdoor termination end to suck the blockage backward out of the line rather than blowing it further inward. When using a compressed gas tool like a CO2 gun, it is crucial to apply the pressure from the indoor access tee toward the outside while ensuring the line is not sealed too tightly in a way that could rupture older PVC fittings or damage the indoor condensate pan.