Attic AC Condensate Drain Line Clogged with Bacterial Algae Slime in Highland Park Pflugerville

Derek_S_HighlandPark Homeowner

Posted in Pflugerville Homeowner Forum • Travis County

Question: I noticed our digital thermostat display went completely blank and the AC shut down completely in our Highland Park home. When I climbed into the attic, the secondary emergency drain pan had 2 inches of standing water and water was dripping onto the ceiling drywall. What happened?

✓ VERIFIED PRACTIONER DIAGNOSIS

Cody_R_TDLR_Tech Texas TDLR Class A Master Tech

Texas Department of Licensing & Regulation Certified

High ambient Texas humidity created zoogleal bacterial slime inside the uninsulated 3/4-inch PVC condensate trap, overflowing the primary drain pan and tripping the secondary safety float switch to kill 24V thermostat power.

Diagnostic Procedure & Field Restoration:

Bacterial zoogleal slime plugged the 3/4-inch PVC p-trap on the attic horizontal air handler.
The secondary float switch properly triggered to prevent complete ceiling drywall collapse by cutting 24V control circuit power.
Flushed drain line with pressurized nitrogen canister, vacuumed secondary pan dry, and installed an accessible clear EZ-Trap with cleanout brush.
Added pan bio-stabilizer treatment tablets to prevent zoogleal bacterial bloom under extreme 135-degree attic temperatures.

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