How long to vacuum an AC drain line?

Vacuuming an air conditioner condensate drain line using a wet-dry shop vacuum is a very quick process, typically taking only two to five minutes of active suction to completely clear out standing water, sludge, and debris. To perform the task correctly, connect your vacuum hose to the outdoor terminal end of the PVC drain pipe, and use a wet-dry rag or specialized adapter to create a tight, airtight seal around the opening. Turn the vacuum on and let it run continuously for about sixty to ninety seconds, which provides enough negative pressure to pull stubborn clogs, mold masses, and stagnant water backward out of the line and into the vacuum canister. You will often hear a distinct change in the vacuum motor pitch or see sludge and water rushing through the transparent hose when the clog breaks loose. Once the suction flows freely, turn off the vacuum and verify the results by pouring clean water down the indoor access tee.