Half the 'AC not working' calls we run in July are clogged drain lines tripping a float switch. The other half are clogged drain lines flooding ceilings. Here's why Florida humidity makes this inevitable, the right way to keep it clear, and what to do when it's already overflowing.
Verified Google reviews
Class-A CAC1824400
Treasure Coast residents
Full-spectrum HVAC
Approved before work begins
Warranties registered for you
A 3-ton AC running 14 hours a day in August pulls 15–20 gallons of water out of indoor air. Every drop runs through a 3/4-inch PVC tube — dark, warm, moist — the perfect environment for algae and biofilm. By month four of summer, the inner tube wall is coated with a half-inch slime layer that catches dust and pollen, creating a plug.
Catch it early and you flush it with vinegar. Miss it and you're patching drywall.
Find the access tee — a vertical PVC pipe with a removable cap, usually within 18 inches of the air handler. Pop the cap. Pour 1 cup of distilled white vinegar slowly. Wait 30 minutes. Run the AC and verify water is now flowing out the outdoor termination. Do this monthly June–October.
Bleach is what the internet recommends and what kills drain pans. Sodium hypochlorite corrodes the galvanized secondary pans, attacks the rubber boots on coil U-bends, and creates chlorine vapor that damages copper. Vinegar is mildly acidic, kills algae just as well, and won't hurt anything in the system. We service systems weekly where bleach has eaten through a pan and started leaking — preventable.
If the float switch has already tripped and vinegar isn't flowing through, head outside to the drain termination (white PVC stub exiting the wall or eave). Attach a wet/dry shop vac, seal the gap with a rag or duct tape, run for 60 seconds. You'll usually hear and feel a slug of biological material slap into the vac canister. Pour a final cup of vinegar to leave the line clean.
We pull the access cap, snake a CO2 nitrogen cartridge through the line under controlled pressure (no PVC damage), and verify free flow. Then we open the air handler and inspect the primary pan, secondary pan, and the coil drain trough. We test the float switch by manually filling the secondary pan and confirming the system shuts off. We install a time-release algaecide tablet in the pan. Total time: 30–45 minutes.
Monthly homeowner vinegar flush during summer. Annual maintenance includes drain inspection and tablet replacement. For attic air handlers we strongly recommend a secondary float switch wired into the air handler's safety circuit — code-required in newer installs, but missing on many older Treasure Coast systems. It's the single best protection against a $5,000 ceiling repair.
“My highest recommendations for Devon and the Maritime Air team — thorough, honest, and on time. They explained everything in plain language and didn't push any unnecessary upsells.”
“Devon has provided thorough maintenance and excellent service. Truly family-owned care — they treat your home like it's their own. Highly recommend for Treasure Coast homeowners.”
“Working with Devon on my HVAC system was a great experience from start to finish. Fair, clean install, and the system has been running perfectly through Florida summer heat.”
Real installs and repairs we've completed across the Treasure Coast.
Florida humidity means your AC pulls 8–20 gallons of water per day out of the air. That water carries dust, algae spores, biofilm, and pollen down a dark 3/4-inch PVC tube. Within months, biological growth creates a slimy plug.
We don't recommend it. Bleach corrodes pan coatings, eats refrigerant line set rubber boots, and can damage metal drain pan secondaries. Use distilled white vinegar or a manufacturer-approved enzyme tablet instead.
Monthly during summer (June–October). Pour 1 cup of distilled white vinegar through the access tee on the drain line. Once a quarter in winter is sufficient.
It's a safety device in the drain pan or drain line that shuts off your AC when water backs up. If you ever notice your AC stopped running but everything else seems fine — check this first. The system is telling you the drain is clogged.
Your secondary drain pan under the air handler overflowed. The primary drain line clogged, water filled the unit, the secondary catch pan filled, and now it's running down through the drywall. Turn the AC off immediately and call for service.
Yes, this is the right DIY approach. Attach the vacuum hose to the exterior drain line termination, seal with a rag, run for 60 seconds. Most clogs come out as a slug of algae and water.
Whether the clog is in the trap, the run, or the pan; whether the float switch needs replacement; access difficulty for attic vs. closet air handlers; and whether secondary water damage repair is needed.
Yes if you have a horizontal air handler in the attic. Time-release algaecide tablets in the pan keep biofilm from forming all season. We install these as part of every maintenance.
Call (772) 236-4277 or schedule online. Class-A licensed across the Treasure Coast.
