How to Unclog an AC Condensate Drain Line (Stop Water Overflow)

Time required: 20-30 mins · Difficulty 1/5

Est. DIY Parts: $8 - $20 · Pro Service: $150 - $250 · Est. Savings: $130 - $240

* Estimates based on regional/national contractor rate benchmarks. Actual part prices vary by brand and retailer.

Parts & Tools You'll Need

Turn off your thermostat and AC breaker Shut off your air conditioning at the wall thermostat and turn off the breaker to prevent the unit from cycling during service.
Locate the PVC drain access T-pipe Find the white 3/4-inch PVC pipe coming out of the indoor air handler/furnace. Remove the unglued slip cap on the vertical T-fitting.
Hook Shop-Vac to the outdoor drain exit Go outside to where the white drain pipe exits near the compressor unit. Seal your Shop-Vac hose to the pipe using an adapter or wet rag.
Run vacuum for 2-3 minutes to suck out sludge Turn on the wet vac and let it run. You will hear brown algae slime and stale water get sucked directly into the vacuum canister.
Flush with 1 cup of white vinegar Return to the indoor T-pipe, insert a funnel, and pour 1 cup of distilled white vinegar down the line to kill remaining bacteria, then replace the cap.