R-Pro › Field cases › Air conditioning
AC Drain Pipe Clog — Slime / Debris Removal
Likely causes
Identify clog cause (slime, insects, dust, poor slope)
Check: Discharge end = if no water flow, clog confirmed. Check end for dust/leaves/insect carcasses. Trap area = slime (mold/bacterial mucus) common. Measure slope (level): below 1% causes stagnation that breeds slime. Ambient <5°C = suspect freeze.
What to do: From discharge end use wet-vac or blower → suction out slime/debris. Avoid rods/wire brushes = damages insulation/pipe. Compressed air reverse-blow = effective but protect indoor unit. After cleaning, spray antimicrobial (vinegar or diluted bleach 1:16). Poor slope = redo piping.
Slime explodes 3–4 weeks after season starts. Spraying antimicrobial at start = 80% reduction. Address clogs immediately — within 1 week or indoor leak develops. Beware copper/aluminum corrosion with bleach — vinegar preferred.
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