What are the signs that my AC drain line is clogged?

A clogged air conditioner condensate drain line presents several clear warning signs that you can easily spot around your home. The most obvious indicator is water pooling or puddling around the base of the indoor air handler unit or water dripping down from interior walls and ceilings near the HVAC closet. Another frequent sign is a musty, damp, or moldy odor emanating from your air vents, caused by stagnant water and organic slime trapped in the drain pan. Additionally, modern air conditioning systems are equipped with safety float switches that automatically trip and shut off the cooling unit when water levels in the drain pan rise too high; if your AC suddenly stops blowing cold air while the thermostat is calling for cooling, a blocked drain line is a very common culprit. Finally, if you inspect the primary emergency drain pan and see standing water instead of it being completely dry, your drain line is restricted or entirely blocked.